Riker suffers a series of disturbing delusions.
Commander Riker finds himself in a mental institution, apparently insane, while he is rehearsing a play about a man who has lost his mind. The reality he knows begins to slip, and he cannot tell what is real. He moves between the stage and the asylum, with no clear way out.
The episode is a psychological thriller with a focus on the question of identity, and it is one of the most unsettling stories in the series. The viewer is kept guessing until the final moments, and the story uses its theatrical framing in an inventive way.