Never do this.
A line used very, very often on messages summoning someone to a meeting between two people on opposing sides.
A variant is one guard on each side.
Almost inevitably, one side or the other will break the agreement and sneak extra people into the area. This side is to be treated as the betraying scum they are, and it doesn't matter anyway, since they will gain no advantage when the other side wipes the floor with them anyway. If both sides break the agreement, then whoever the audience first learns cheated are the scum; it's not fair, but it's true. Alternatively, the Good Guy will indeed come alone, but the rest of the team will try to follow discreetly and instead be discovered, thus ruining the Good Guy's efforts.
- In Code Geass Suzaku tells Lelouch to come alone to the Kururugi Temple. Both sides honor the agreement, but Suzaku is secretly followed by Schneizel's men and Lelouch is arrested. Lelouch screams bloody murder and Suzaku is left feeling miserable. Lelouch rightly stops trusting Suzaku after this point, but Suzaku curiously goes right back to antagonizing Lelouch.
- In Death Note, the finale takes place when Light and Near agree to meet with each other in a warehouse, each bringing only the few people working with them on the official investigation. However, Near knows that Light will have Teru sneak in as well, and Light knows that Near knows this (as well as that Near knows he knows this), and...
- Gungrave anime uses this trope when Blood Knight Bloodwar invites Brandon Heat into abandoned warehouse for duel. Played straight as Bloodwar didn't come alone.
- Played straight and then subverted in Baccano!. Jacuzzi comes alone. Then the rest of his gang comes alone. But they bust in together. And then Claire comes alone with them.
Graham Specter: I don't know how I can argue with that logic.
- In an issue of Thorgal ("Aaricia"), Thorgal, as a young boy, is challenged by the chieftain's son to a solitary duel on a remote island. Both sides of the trope come in effect, with the evil chieftainling sneaking a pair of goons into the area, and Aaricia sneaking herself in secretly to aid Thorgal.
- Spoofed in a commercial for Verizon Wireless, stressing the reliability of their network: a man shows up to a meeting with black-clad criminals, who angrily insist that he was to come to the meeting alone. We pan back to find the entire cell-phone network, which includes thousands of people and a couple of helicopters, standing directly behind him. The head bad guy seems more intrigued than angry and wants to know if they work down at the docks too.
- Well, what do you expect? "Verizon Wireless: Sign up now for free Cement Shoes" isn't a very market-friendly slogan.
- In The Big Lebowski, when The Dude is dropping off the ransom money, the Nihilists demand he comes alone. This prompts Walter to describe them as "fuckin' amateurs."
- Played straight in The Bourne Identity, where the CIA at least have the sense to disguise their man's backup as innocent bystanders. Unfortunately they underestimated Jason Bourne.
- Farewell My Lovely. A man on the phone tells the Private Eye protagonist to come alone and unarmed. He takes a gun out of the drawer, and the Private Eye Monologue informs us that when someone tells you that, it's time to bring a gun that works.
- Subverted in The Bourne Identity, where Jason Bourne requests it before meeting the head of the CIA. When the guy brings hidden snipers and such, Bourne calls off the meeting. Turns out Bourne was expecting the guy to bring backup, and the real purpose was to get him to a known location so he could plant a tracker on his car.
- In J.R.R. Tolkien's Silmarillion, when Morgoth offers to discuss the return of the Silmarils with the sons of Feanor, both sides come with more strength than agreed upon.
- But Morgoth brought the more, and there were Balrogs.
- In The Godfather Michael Corleone is summoned to such a meeting after the Don has been shot.
- Artemis Fowl: The Eternity Code starts with Artemis meeting Jon Spiro in a restaurant. Butler is twitchy about the place being unsecured, and Artemis quips that the little old lady over there probably isn't a trained assassin. She is. And so is everyone else there.
- Done again by Opal Koboi in "The Opal Deception. She (posing as goblin criminal Scalene) insists that Holly Short and Julius Root (the LEP fairies most directly responsible for Opal's downfall) come alone when they are attempting to capture him. They follow his instructions. It does not end well.
- Double subverted in Discworld, when Vimes is asked to come alone to a meeting with Chrysophrase the Troll. He doesn't come alone, and neither does Chrysophrase. They trade some snide remarks, order their followers outside, and proceed to have as civil a conversation a chief of police and a known Breccia boss can have.
- Subverted in Dorothy L. Sayer's Gaudy Night; heroine gets such a message and remembers hero's remark that characters in books that fall for that are idiots, so she takes precautions.
- Babylon 5: Subverted. Dr. Franklin informs Captain Sheridan that he has been contacted by the Telepath Underground Railroad, an organization that helps telepaths escape from the Psi Corps. They want to meet with Sheridan, but Sheridan must arrive alone. Sheridan obeys, and comes to the meeting place to find Dr. Franklin waiting for him. Franklin wanted to be sure Sheridan could be trusted before revealing his part in the whole thing.
- On Charmed, the Halliwell Sisters found themselves in the position of arranging a supposedly peaceful meeting with some demons, and it seemed like it would be safe to arrange it in a crowded restaurant. However, the demons' cheated on their agreement to come alone, and in fact they replaced every single person in the restaurant with a demon.
- In a first-season episode of Law & Order: SVU, Olivia is being stalked by a killer. He calls and requests a meeting, telling her to come alone. Not being an idiot, she takes substantial backup and they catch the killer. Two seasons later, she's again being stalked, and again is told to come alone. Having apparently lost brain cells since season 1, she goes alone, and ends up having to shoot the bastard.
- On one NCIS episode, Gibbs arrests a mob boss's son, and goes with an FBI agent to learn who the mob's mole is. The mob boss, of course, shows up with backup. Gibbs, of course, has det cord, which he wraps around the kid's neck, allowing him to kill him with the push of a button. The mole, is, of course, the FBI agent, who is shot by Gibbs' sniper when he tries to shoot Gibbs. Hilariously, the mob boss abandons his son to a few years in the pen, claiming it's good for developing character.
- The mob boss does actually ask Gibbs to come alone at first, but Gibbs breaks out in hysterical (for him) laughter and tells him that he's not that stupid.
- On Burn Notice, Mike's ex-fiance's son is kidnapped. He sends Sam with her to meet with the kidnappers, since he knows the kidnapper won't blow the deal over just one bodyguard.
- In The Tenth Kingdom, the Evil Queen meets with Relish the Troll King, telling him to "come alone and unarmed" or she would slit his children's throats. Of course he doesn't, instead coming an hour early and hiding his men among the trees of the apple orchard. Not to be outdone, the solitary Queen was there two hours early and poisoned all the apples.
- Pretty Guardian Sailor Moon has a slightly Genre Savvy, if somewhat stupid good, Usagi subvert the usual outcome of this trope. Receiving a "come alone" message from Dark Mercury, she realizes her friends would follow her anyway, and so lies to them about the meeting's location. In another subversion, Dark Mercury actually does show up alone too, but that doesn't keep Usagi from nearly getting killed.
- In the first season of 24, Victor Drazen warned Jack Bauer to come alone for the final showdown at the docks if he wanted to get Kimberly back. Jack did come alone, though CTU got word of what he was doing and sent a team, only to find that Jack had already taken everyone out. There are probably other instances throughout the series as well.
- Occurs frequently in The Rockford Files. However, it is notable for having the hero cheat every time as well as the villains.
- Happens in the final episode of Kamen Rider Decade, as Tsukasa is summoned by Apollo Geist. Of course, neither side ends up fighting alone, and what results is a free-for-all between various monsters and riders.
- Lampshaded and discussed in Nowhere Man. Thomas Veil is an Unperson who is being called by a Mysterious Informant with information about why his life was taken away. He schedules a time and place for them to meet. A suspicious Tom tells him he forgot to say come alone. The informant didn't say it because he knows in Tom situation he has no friends or anyone he can trust so he felt no need to mention it.
- Played for Laughs as always in Buffy the Vampire Slayer. Buffy receives a phone call from Spike as sinister music plays.
Spike: (talking in a low voice) Slayer...
Spike: Meet me at the cemetery. Twenty minutes. Come alone.
Spike: Bloody hell (music cuts off and Spike talks normally) Yes, it's me.
- Angel. After Wesley is expelled from the Fang Gang, evil lawyer Lilah Morgan sends him an anonymous email asking for a meeting with "Come Alone"—when Wesley turns up she taunts him that of course he was going to come alone, as he no longer has any friends.
- Played Straight in Grand Theft Auto 4. You are told to come alone to be paid by Dimitri, but Genre Savvy Little Jacob insists on coming. Naturally, it's a double-cross and the two of you have to blast through tons of Mooks.
- Also played straight in Saints Row, for the final mission. The boat explodes. The only person that survives is the Player, and he's comatose for 5 years.
- In Advance Wars: Days of Ruin (Dark Conflict), there is a scene like this, in which the Big Bad and the hero agree to meet alone. They're accompanied by The Lancer and The Dragon, and while the Lancer is revealed first, it's established that she came without the hero's knowledge. On the other hand, the Big Bad probably brought the Dragon along on purpose.
- This happens in Heroes of Might and Magic IV, in the final mission of the Light Campaign, where you storm the villain's capital, you only find a note saying: "Come to the nearby cave, alone, and we will duel to the death." You are forced to accept the ridiculous demand only to find out the villain has hired a host of thieves to his aid. The battle is, nonetheless, easy.
- Lampshaded in Knights of the Old Republic II after the crime boss Visquis invites the Jedi Exile to meet him at a Bad Guy Bar and insists that she come alone:
Atton Rand: [sarcastic] Well, good thing it's not a trap.
Mical: No, Atton, I think it may be a trap!
- Played straight in the previous installment where Hulas would not talk about the Genoharadan while you had other characters in your party and encouraged you not to take anyone along on your missions for him. It also subverts it since you can bring your party members on the missions. At the end of the quest line, if you challenge Hulas to a duel he tells you to come alone. He comes to the duel with a small army regardless of whether you bring anyone and mocks your gullibility.
- In Guild Wars 2, as a couple of lower-caste charr bargain with you to join them alone in the woods to assist them with a job. Even your party is Genre Savvy enough to warn you that it's a horrible idea. But in the end, the trope is subverted when they completely fulfill their end of the bargain with no shenanagins. One of them lampshades the trope in response to your character's surprise of their trustworthiness.