John Winston

A machine that destroys planets threatens the Enterprise.

The Enterprise is thrown back to 20th century Earth.

Accidentally overdosing on medication, a psychotic McCoy leaps through a time portal into the 1930s and somehow disrupts Earth's future so that the Federation and Starfleet do not exist. The stranded Kirk and Spock follow him back to set things right, where a tragic love tests Kirk's resolve.

Kirk meets Khan, a leader of Earth's Eugenics War.

Kirk, Scott, McCoy and Uhura enter a parallel universe.

Aliens on a mission of conquest hold the crew captive.