Picard and Riker work undercover among mercenaries collecting pieces of an ancient Vulcan psionic weapon.
Picard and Riker continue posing as turncoats aboard Baran's ship while Data commands the Enterprise. Tallera tells Picard she is a Vulcan security officer working undercover, and the pieces turn out to belong to the Stone of Gol, an ancient Vulcan psionic weapon that turns aggressive thoughts into a deadly force.
Baran tries to kill Picard with the neural device he uses to control his crew, but Picard has altered it and Baran dies instead. Tallera assembles the Stone and is revealed to be a Vulcan isolationist who wants to use it. Picard realises it only works on violent minds, so he has everyone clear their thoughts of aggression, the weapon fails, and Tallera is taken into custody.