About Star Trek: The Next Generation Season 3, Episode 18 : Allegiance

Stardate: 43714.1 Picard is secretly abducted and switched with an alien double. The crews' suspicions are raised when he starts exhibiting unusual behaviour, and is relieved of command. Guest Stars: Jeff Rector, Reiner Schöne, Joycelyn O'Brien, Jeff Rector, Stephen Markle,