Summary: Samantha and Darrin are in the town of Inverness, Scotland, which is famous for Loch Ness, a large lake fed by the River Ness. They are visiting Darrin's cousin Robbie who owns a resort hotel on the Isle of Skye.
Robbie tells Sam and Darrin that the monster of Loch Ness - which is the biggest tourist attraction - has been very shy. Just then they see a creature with a long neck and the head of a dinosaur rise from the water. Robbie and Darrin faint. Samantha tells the monster (who is really a former warlock, Bruce), to get back in the water. She revives Darrin and Robbie and they go to the Inn where they meet Baron Von Hauser. The Baron, who has a mini-submarine, tells Sam and Darrin that he is trying to capture the monster and collect the $3 million reward money.
Samantha explains to Darrin that the monster, Bruce, was a friend of her cousin Serena. He hounded Serena so much that she turned him into a monster...and she is the only one who can restore him. Sam decides to summon Serena to save Bruce's life.
Serena arrives and the three go out on the lake in a row boat. Serena goes below and changes Bruce back to the obnoxious warlock he used to be. Bruce, filled with bitterness at Serena, decides to get even and gives her the tail of a mermaid.
Sam and Darrin are shocked when they see Serena and Darrin tries to carry her back to the Inn. Of course, everyone is curious about Serena's "injured" leg. Samantha zaps Bruce into the room and, just then, Robbie bursts in to say that the Inn is swarming with reporters, photographers and TV men who want to televise the monster in action.
Serena says she will have to be the Lake's attraction since Bruce is no longer the monster. But now that there will be publicity, Bruce wants to become the monster again. He changes Serena back and she in turn changes him into the Loch Ness Monster...and everyone is happy.
Courtesy: Bewitched & Elizabeth Montgomery Page