Project Genesis, Khan's revenge and the death of Spock

In 2285 the USS Reliant was searching for a lifeless planet to test Project Genesis, a device developed by Dr Carol Marcus and her son David that could transform a dead world into a living one in minutes. Arriving at what they believed was Ceti Alpha VI, Commander Chekov and Captain Terrell found Khan Noonien Singh, marooned fifteen years earlier on Ceti Alpha V. The neighbouring planet's explosion had turned the colony into a wasteland and killed many of his people, including his wife.

Khan seized the Reliant, stole Genesis and set out to destroy Kirk, by then an admiral overseeing a training cruise aboard the Enterprise. After a surprise attack crippled the Enterprise, Kirk outwitted Khan in the Mutara Nebula, where their ships fought half-blind. Mortally wounded, Khan triggered the Genesis device to take his enemy with him.

The Enterprise could only escape if its warp drive was restored. Spock entered the radiation-flooded engine room and repaired it, saving the ship at the cost of his own life. His body was laid to rest on the new Genesis planet that the explosion had created, and Kirk discovered that David Marcus was his son.