Gamma Trianguli VI is a peaceful planet with abundant plant life. It seems a paradise, but the landing party soon feels the thorns: poisonous plants, killer storms, and explosive rocks all claim lives. Eventually, they discover a small community of primitive people who serve the mysterious Vaal, an immense statue, chiefly by feeding it when it demands this. These people live immensely long lives, and do not age or procreate unless there is an accident. Theirs is a stagnant society, and into the bargain Vaal apparently has the means to attack the Enterprise...

Sulu, Scotty and Jackson explore Pyrus VII, and then Jackson calls the ship, "one to beam up". He materializes dead, and a sepulchral voice threatens Kirk, saying his ship is cursed! Beaming down, Kirk discovers his men enslaved by strange aliens, who have created a Gothic castle and other artifacts straight from Halloween. But their power and threat are real - they are from a place so alien, that the sensations of this universe are intoxicating. If not stopped, they pose a grave threat to the Federation.