Back on Earth enjoying a well-deserved shore leave, Captain Kirk is rudely accosted by a trio of Starfleet Security guards. He is wanted for questioning in connection with the theft of transwarp, the Federation's newest most advanced propulsion system. With the aid of Mr. Spock, Lt. Cmdr. Piper begins a desperate search for the scientists who developed transwarp, a search that leads her to an isolated planet where she discovers the real and very dangerous traitor!