While searching for survivors of the Starship Archon which disappeared under mysterious circumstances, the crew of the Enterprise encounters a culture of zombies controlled by the computer Landru. Landru regulates the life of all planet members, purging their systems of violence and anger at specified times known as ``festivals'' and leaving them blankly contented for the rest of the time. Landru succeeds in absorbing Sulu, and attempts to do the same with the rest of the crew. When Kirk points out to Landru that he has violated his program by allowing human culture to stagnate, Landru disintegrates in a shower of sparks and frees the planet from his control.