Star Trek III: The Search for Spock (Paramount Pictures, 1984) is the third feature film based on the Star Trek science fiction television series. It is often referred to as ST3:TSFS or TSFS. It is the middle chapter in a loose trilogy, preceded by Star Trek II: The Wrath of Khan and concluded in Star Trek IV: The Voyage Home.

Picking up where exactly where Star Trek II left off, the Enterprise and crew are returning to port for some essential repairs to their ship. When they arrive, they are shocked to discover the Enterprise is to be scrapped. When Dr. McCoy starts acting strangely, Kirk is forced to steal his old ship back and fly across space to a lonely planet to save a friend. Written by Colin Tinto

With most of the Enterprise's battle damage repaired after defeating Khan at Genesis, the ship's crew returns home to bad news from Starfleet Commander Morrow: the Enterprise is to be decommissioned. Even worse, Dr. McCoy begins acting bizarrely. A visit to Kirk from Sarek - Spock's father & the Vulcan ambassador - reveals that McCoy is carrying Spock's Kattra, or living spirit. Immediately, Kirk meets with Admiral Morrow to plead for permission to return to Genesis and rescue Spock. When permission is denied, Kirk & his crew steal the Enterprise and head for Genesis - by now a quarantined planet. Unknown to them, the Klingons, led by the psychopathic Commander Kruge, are planning to steal the secrets of Genesis for their own twisted purpose. The Enterprise is crippled in a fight with the Klingon ship, and worse, the Klingons murder Kirk's son, who was among the science team that rescued Spock. Kirk eliminates the remaining Klingons by tricking them aboard the Enterprise and then blowing it up with the auto-destruct, then steals the Klingon Bird of Prey and heads for Vulcan for a ceremony to re-fuse Spock's body and Kattra. Written by Derek O'Cain

Admiral Kirk's defeat of Khan and the creation of the Genesis planet are empty victories. Spock is dead and McCoy is, seemingly inexplicably, being driven insane. Then an unexpected visit from Sarek, Spock's father, provides a startling revelation: McCoy is harboring Spock's living essence. With one friend alive and one not, but both in pain, Kirk attempts to help his friends by stealing the Enterprise and defying Starfleet's Genesis quarantine. But the Klingons have also learned of Genesis and race to meet Kirk in a deadly rendezvous. Written by Robert Lynch