Impossible Mission

A standard television and film plot. An assignment is received in The Teaser. A planning session is held (Avengers Assemble), complete with an Obstacle Exposition. Sometimes an Unwinnable Training Simulation follows, just to underscore how difficult the task is. Then comes The Caper or The Con, often using a Master of Disguise and an A-Team Montage. The resolution is as close to end of The Tag as possible. At about the 40-minute mark, there is a Pseudo Crisis. An Unspoken Plan Guarantee will almost certainly be in play, either obviously or carefully hidden -- and sometimes an Impossible Mission Collapse will complicate matters immensely.

If it involves Cool Planes, it becomes an Airstrike Impossible.

"Caper films" share the same basic structure, with different timing and sometimes without the assignment being assigned.

The trope takes its name from the series Mission: Impossible, whose Impossible Mission Force did one of these every week. As such, note that not every impossible mission is an Impossible Mission.

For missions that actually are impossible, see Impossible Task.

Not to be confused with the video game Impossible Mission. Also see Suicide Mission.

Examples of Impossible Mission include:

Fan Works

The story "Diamonds in the Desert" from The Midnightverse.

Film

The eponymous task of "Inception" in the film of the same name.
The League of Gentlemen is probably the Ur Example of the trope.
The National Treasure film series includes some of the loftiest ever devised, from stealing the Declaration Of Independence to kidnapping the President of the United States.
Ocean's Eleven and its sequel, Ocean's Twelve both hit almost all the common features of an Impossible Mission.
Naturally, the various Mission: Impossible films.

Live-Action TV

Despite its few episodes, Firefly did two of these, in "Ariel" and in "Trash".
Mercilessly parodied in the Whose Line Is It Anyway? game "Improbable Mission," which had agents given missions involving high stakes but ordinary tasks, such as doing laundry or mowing the lawn.
The Farscape episode "Fractures" (S03 E18): Crichton's run on the Command Carrier.
And of course there is the Trope Namer and Trope Codifier, Mission: Impossible.

Real Life

The plot to kill Hitler during WWII (known as Operation Valkyrie) came close to a real-world expression of this trope.