Star Trek: The Motion Picture - Echoes #3

Akris-a maniacal doppelganger of Chekov from a parallel universe-has begun working with the Romulans on a superweapon with a promise to reduce the Federation and its allies to ash. But with half the bridge crew in Romulan custody, it's up to Spock and McCoy to hold down the ship and devise a plan to get their captain and crewmates out of enemy hands!