Interrogated for Nothing

"I fear you speak upon the rack
Where men enforced do speak anything."

—William Shakespeare's The Merchant of Venice

Our Hero has been captured. He's being asked questions, and has folded under Cold-Blooded Torture or Truth Serum. And then they ask what the plans are for something he doesn't know. Of course, they will believe he is somehow resisting, hiding that vital knowledge. So, the cruelty intensifies.

Harshly ironic, since our hero is suffering a great deal because his captors refuse to believe that he doesn't know anything. No, they are certain that if they just push him a bit further, he will crack and give them what they want.

A frequent subversion, for Kick the Dog points, is for the captor to either realise or already know our hero doesn't have the information...and to keep going anyway.

It should be noted that a problem with upping the torture is, if it works, the captured will tell his captors anything to make the torture stop, regardless of whether or not it's actually true. And some really, really inventive and plausible stories come out of them. A person who has nothing to spill, will desperately try and find something, or make it up. See also Torture Always Works.

Examples of Interrogated for Nothing include:

Anime and Manga

Death Note has a variation, where L imprisons and interrogates Misa on completely accurate suspicions that she is the second Kira... unaware that, through a trick of the Note, all of her pertinent memories have been erased. This goes on for a month before the team convinces him to try something else.
Now and Then, Here and There: This happens to Shu during the first few episodes. Worse, Abelia is quite aware from the begining that he doesn't know anything but is forced to keep torturing him, on King Hamdo's orders.
Near the end of Last Exile, [[spoiler:Alex Rowe is given a Truth Serum by Delphine in order to obtain the information that she needs. It turns out that Alex never entrusted himself with the last piece of the poem, predicting the possiblity of being captured and interrogated.
In Ah! My Goddess, Urd, while in Lord of Terror mode, briefly tries to torture Keichii for information about the Ultimate Destruction Program. She quickly learns that all he knows about it is the fact that it exists.

Comics

In a V for Vendetta bonus comic from the TPB, two Finger men do a prolonged interrogation of a suspect, then force him to walk around the ledge on the high rise building, which is virtually certain to lead to his death. After forcing the suspect outside, one asks the other if he really thinks the suspect actually has any connection to V. The second says no, but that he and his wife are having some killer fights at home and he needs to take it out on someone.

Film

Marathon Man: What the Nazi dentist played by Sir Laurence Olivier does to Dustin Hoffman ("Is it safe?"). The actual scene is brief, and the torture rendered mostly by implication; but it is still arguably the most chilling example of this trope in cinematic history.
The James Bond franchise has been known to do this on occasion, most notably in the opening theme of Die Another Day. During that theme, Bond is put through a who's who of torture methods, and it's later revealed that he was intentionally given an incomplete briefing by MI6 for his mission, just in case he was captured. They do trade someone important for his return though, which he never expected to happen, and calls them out on.
A version of this is the focus of Slumdog Millionaire, where Jamal is tortured to find out how he cheated. At his repeated insistence, the two cops eventually acknowledge that he might be telling the truth about not cheating a few hours in. After they stop torturing him and interrogate him somewhat more civilly, Jamal tells them, in the form of flashbacks to his life story, exactly how he was able to get each answer right.
In To End All Wars, Yanker is viciously beaten with a shovel after one goes missing and he admits to taking it to keep everyone else from getting killed. It isn't till after he's paralyzed that the commander discovers that there was just a miscount and none of the shovels are missing after all.
This is the whole point of the film Rendition; they bagged the wrong El-Ibrahimi. They're torturing an innocent man.
Ichi the Killer: A horrific torture scene occurs when the sadomasochistic Yakuza Kakihara is led to believe that a Yakuza from another gang is responsible for the disappearance of his boss. The man is completely innocent, but the gruesome damage is done by the time they realize it.
Mentioned in Dr. Strangelove. When General Ripper is realizing he's about to be arrested for treason and tortured for the recall codes, he suddenly asks Mandrake if he's ever been tortured as a war prisoner. Mandrake explains that he was captured and tortured by the Japanese during World War II. When asked if he talked, he explains they didn't seem to want any information. Ripper kills himself shortly afterward. It's all funnier than it sounds.

Literature

The Terrorizers: Donald Hamilton's Matt Helm novel. Secret agent/assassin Matt Helm is captured by the enemy, who torture him to find out vital information. Unfortunately he has amnesia, so he can't tell them anything. They think he's faking and continue the torment.
Robert Heinlein's Friday. The title character voluntarily spills her guts to her interrogators, which is standard policy for her organization as a highly trained courier is far more important than any piece of information they may be carrying at one time. As her boss knows anyone will eventually crack, he deliberately withholds information about anything important. After questioning her under Truth Serum and getting the same story, they decide she's been hypnotically conditioned to tell false information and ruthlessly torture her. The interrogators end up respecting their victim as the only person they couldn't crack under torture.
The climax of Foucault's Pendulum involves a group interrogating the hero about a plan. Not only does the hero not know the plan, it doesn't even exist.
In Roswell High, towards the end of the first season Max is being held by evil government people who torture him into telling them various things. But then they want him to show them how to use some device that he has no clue how to work (or he'd have already used it), and start to cut him open when he doesn't.
In the third and fourth Tennis Shoe Adventure books, Garth is captured by the current Big Bad (King Jacob) who wants the location of a fabled treasure. Garth was looking for the treasure, but never found it. King Jacob doesn't believe this, so he goes after Garth's family, finally kidnapping one of his nieces. Her torture, apparent death and subsequent recovery and a Heroic BSOD follow. Eventually, King Jacob realizes that Garth doesn't know, and leaves.
An ironic variant in Flashman and the Mountain of Light: the Sikh high command captured Flashman and, Dirty Coward that he is, he told them everything before they even showed him the torture instruments. Which convinced them, since they believed his reputation, that he was concealing information of great importance, because no one as heroic as the great Flashman would spill the secrets so readily unless giving out false information was worth seeming like a coward. One of the Sikhs had tears of admiration in his eyes as he told Flashman they were going to torture him until he gave them the "truth."
In a Star Wars short story, Corran Horn helps a group of rebel sympathizers escape an Imperial Prefect, while simultaneously framing the man for rebel sympathies and murder. Horn's thick-skulled Imperial liaison (when he was still working for CorSec) takes the overseer away for an interrogation session, with the innocent man mentally remarking how bitterly hilarious it is that he will be tortured endlessly for information that he doesn't have.
Ethan of Athos: Ethan is captured and questioned by the Cetagandans about the location of Terrance Cee, first using a truth serum, and then upping the ante to more and more painful methods. Since this is the first Ethan's ever heard of Terrance, he tells them he doesn't know who they're talking about, right from the beginning.
In The Princess Bride, Humperdinck and Rugen torture Westley for weeks about for the name of the Guilder official who commissioned the abduction of Princess Buttercup. Not only would Westley not know this information as he was not the kidnapper, the information didn't exist at all, as Guilder wasn't involved. And Humperdinck knew this, as he was the one who had ordered the kidnapping.
Subverted (or maybe zig-zagged) in Sartre's short story "The Wall." The protagonist / narrator is told that he will be shot at dawn if he does not give up the location of Ramon Gris. He knows where Gris is, but gives them the wrong information, saying he's in the cemetary. He does it more to be a smart ass and make fools of his captors than anything. They don't kill him, because they actually find Gris in the cemetary. The protagonist didn't know Gris had gone there.

Live Action Television

Star Trek: The Next Generation: Picard refuses to give up the Minos Korva defense plans under truth serum. How? Because he has no idea what they are. His captor, Gul Madred, works it out eventually...and keeps going, switching his focus to simply breaking Picard for its own sake, via "How many lights do you see?"
24 had at least two victims, a CTU analyst and the Secretary of Defence's son, who the good guys torture to no avail.
Lost: Sayid tortures Sawyer because he and Jack think he stole Shannon's inhalers. Only after shoving sticks of bamboo up under his finger nails for a few agonizing minutes does Sayid learn that Sawyer never had the inhalers in the first place, and was being so stubborn just so he could get a kiss from Kate.
On Rookie Blue Sam is tortured by a criminal who wants to know who killed the criminal's family and why the cops covered it up. Sam knew the guy's family was dead but had no knowledge of the rest. The criminal realizes that Sam probably knows nothing but decides to continue just to make sure.
In Supernatural's season 4 episode "On The Head Of A Pin", the angels have captured Lilith's dragon Alistair and force Dean to use his knowledge of torture from his time spent in Hell for information about how the demons are killing angels. Alistair proves Too Kinky to Torture, however, and merely plays along because he's amused by the emotional trauma reliving his time in Hell is causing Dean. Dean's brother Sam is finally able to force Alistair to talk using his Psychic Powers, only to have him reveal... Nothing. Turns out, the demons weren't behind the murders after all -They were committed by a rogue angel intent on freeing Lucifer from Hell. An odd case in that it was the interrogator and not the victim who was suffering, but it still ended up being for nothing.

Tabletop Games

The Dungeons & Dragons source book Book of Vile Darkness provides rules for torture, which provides a bonus on Intimidate checks made during interrogation. If the victim successfully resists or doesn't know any relevant information, he gets a bonus on Bluff checks to lie to the torturer.

Video Games

In Mass Effect 2, Shepard and his/her squad come across a prisoner being brutally beaten by a guard while on a mission to pick up a convict from a prison ship. (Shepard has the option of convincing or intimidating the guard to stand down.) It isn't made clear whether the guards are looking for information or not, but speaking with another prisoner strongly implies the guards are just torturing him as punishment for 'offing' another prisoner, knowing full well he doesn't have anything to tell them. It's the Cowboy Cop who points out that it's just meaningless cruelty.

Garrus Vakarian: You don't even get good information that way. After a point, victims admit to anything to make the pain stop.

Midway through Final Fantasy VIII, Seifer subjects Squall to Electric Torture, demanding to know the "true purpose" of SeeD, the mercenary organization which trained both of them. Squall not only doesn't know, he has no earthly idea what Seifer is even talking about, making his only options "make something up" or "try to get the interrogator to kill him."

Web Comics

The Order of the Stick does this, although actual torture isn't shown (thumbscrews, water torture and the rack are all mentioned). Instead, he's told that innocent people will be thrown off a tower into a horrific snarl in space-time if he doesn't give up the information he doesn't know (and a control group will be thrown off the other side, just off the tower, not into the Snarl. For Science!!). Notably, the fact that he maintains his claim of ignorance in face of this threat confirms his torturer's suspicions that he's telling the truth, while the actual torture didn't.

Western Animation

Arcee's backstory in Transformers Prime involved her being captured by Airachnid, who brutally tortured her in order to gain attack coordinates. When that failed, Airachnid threatened to kill Arcee's partner Tailgate unless Arcee gave her the coordinates. Unfortunately for Arcee, she genuinely didn't know the coordinates, leading to the loss of her partner when Airachnid refused to believe her.
In My Little Pony Friendship Is Magic episode "Party Of One", Spike honestly has no idea what Pinkie wants to know during his interrogation, so simply tells her what she wants to hear. Ironically, he might have known or guessed about the surprise party Pinkie's friends are holding, so if she'd merely asked him what her friends were doing that afternoon, he might have been able to tell her, and avoid all of the unpleasantness.

Real Life

There's one story about a man tortured by the Khmer Rouge who told interrogators that he was The Pope, a Hermaphrodite, and an American spy. As some have said, presumably the interrogators were feeling bored that day.
Up until the Nineteenth Century, people in Europe were often accused of witchcraft. The vast majority of the accused, believe it or not, were not witches. This did not stop the interrogators from torturing them in an attempt to gain a confession of witchcraft. In the event that the accused made no confessions, they were deemed to be obstinate and the level of torture was escalated until they either did confess or expired.

It's a pretty fair bet that in this case, they weren't just looking for an admission that yes, you were practicing dark magic; they were after a recantation, too. After which they'd probably kill you anyway, although in a much less harsh fashion than burning, in order to safeguard your soul from future temptations.

- Not to mention that, if you were convicted, all your worldly possessions and wealth would become the property of the witch hunters, so there wasn't a lot of incentive to find you not guilty...
  - This was ironically enough one of the reasons why many Catholic clergymen turned against the Witch Hunts, as they often gave final confessions to accused 'witches' who tearfully admitted that they'd lied, even know they faced a horrible death, just to end the torture. Unfortunately the mostly-secular witch hunters ignored this with a "Just goes to show you, those bloody priests don't know how to handle these witches."
- This is still done today in Witch Hunts throughout the Third World, except when they go straight from accusation to the 'incredibly brutal execution' phase. Oh, and they very often kill most of your relatives too, just in case the witchcraft is In the Blood.
  - There is again a profit motive, the victims are often poor people (e.g. old single women) killed when the family is too poor to afford their keep. It's a way to provide moral justification for putting your elders out in the snow, in the absence of snow. Shamans who claim to be able to cure witches do so by taking them in and paying for their keep until things get better and the person is 'cured' (rituals are involved, as well as paying for their keep).