An alien virus strips the enterprise crew of their inhibitions, causing chaos as each crew member is overcome by hidden emotions. Meanwhile, the Enterprise is being pulled inexorably into a nearby planet's gravity well.

Contacted by one of the other two witnesses to the crimes of mass murderer “Kodos the Executioner,” Kirk is persuaded that the criminal may be disguising himself as an actor in a traveling theatrical troupe.

Captain James T. Kirk becomes obsessed with destroying a deadly entity he once encountered in his youth.