Knockout Ambush

The heroes of a story are suddenly ambushed but are shot with Tranquilizer Darts, or something with a similar effect, and not lethal weapons, because the ambushers want them alive.

Usually the scene will involve the darts coming out of nowhere before those being shot at even see their attackers. The heroes are walking along, when all the sudden - zip!, Alice goes down. Followed by Bob and Charlie, and the screen fades out.

Sub Trope of I Want Them Alive. Often involves Instant Sedation

Anime

 * Happens to Vanessa and Madlax in Madlax, when they are captured by Enfant.

Comic Books

 * Happened in an old issue of the Bionic Woman comic. Thugs shot Jamie Sommers, apparently killing her. Then the thugs mention that she was shot with "medicated wax pellets", drugging her into unconsciousness.

Film

 * In Hudson Hawk, Almond Joy takes out Eddie, Tommy Five-Tone and Anna using curare-tipped blowgun darts.
 * In Star Wars, the Jawas ambush R2-D2 and C-3PO with ionization blasters designed specifically to disable droids.
 * In Hannibal, Hannibal is ambushed and captured by mooks wielding some sort of stun gun.
 * In the Stargate movie, soldiers are knocked out by the blunt ends of staff weapons one by one.
 * In Surfs Up, the Pen-Guans take out Chicken Joe (and the cameraman) with blowdarts, right after Joe says that "the jungle is the most peaceful place on the planet."
 * In The Incredibles, Mr. Incredible is taken down by cannons shooting expanding globs of a mysterious substance that eventually immobilize him.
 * Monsters vs. Aliens: "Is he talking about Area fifty..." *zip!* *thud!*

Literature

 * In Firestarter, agents of The Shop capture Andy and Charlie McGee by shooting them with tranq darts from long range. Which was smart considering Andy can control minds and Charlie is pyrokinetic.

Live Action TV

 * Happened to Sheridan on Mars in an episode of Babylon 5. Subverted in that rather than just go down for the count, Sheridan is able to fight his attackers for a short time before succumbing to the tranquilizer patch that had been slapped on him by.
 * Frequently used in Heroes when taking down superhumans.
 * Happened on Lost when Michael leads Sawyer, Kate, Jack, and Hurley to the Others' camp. The Others ambush them from the trees using tranq darts, then gag them and put bags over their heads.
 * In My Name Is Earl, after Darnell is identified as a former secret agent, Earl and Randy keep being shot at with tranquilizer darts as a Running Gag.

Video Games

 * At one point in Half Life you're knocked out from behind by a couple of soldiers.
 * In Fallout 3 you are.