It's the 23rd century in director Leonard Nimoy's Oscar-nominated sci-fi adventure, and a mysterious power is threatening Earth by evaporating the oceans and destroying the atmosphere. To save mankind, Capt. Kirk (William Shatner), Dr. McCoy (DeForest Kelley) and the rest of the Starship Enterprise crew travel back in time to 1986 San Francisco, a world as alien to them as anything they've encountered in their travels through the galaxy.