After landing on planet M-113, the Enterprise is stalked by a creature which can assume the shape and form of anyone it chooses, and which kills by removing the entire salt content of its victims' bodies.

The Enterprise helps Charlie Evans, the lone survivor of a transport crash 14 years earlier, but he threatens the security of the ship when he exhibits strange and unusual powers.

Two crew members develop god-like ESP capabilities when the Enterprise passes through the edge of the galaxy while searching for the Valiant.

While investigating the deaths of a research team on Psi 2000, the Enterprise is infected with a virus that causes crew members to behave irrationally.

A transporter malfunction causes a double of Capt Kirk to appear, one that embodies his wild, negative side.

A slippery con man and his three stunningly beautiful lady friends make a big impression on the Enterprise.