The M5 is a new generation of computers in the 2360's. It's inventor, Dr. Richard Daystrom is convinced this computer will revolutionize space travel and enable starships to go on voyages without the need of a human crew.
In 2268, the M-5 is installed onto the Enterprise for testing. In early tests, the M-5 functions perfectly. But afterwards, the M-5 does not return manual control of the ship and resists the crew. Captain James T. Kirk is able to win back control.