 It s half-term, and Mildred and her friends set off to visit Algernon at his riverside retreat. Mildred has been told to leave her cat behind, but when no one is looking she manages to smuggle him away with her. Much to Mildred s delight, she discovers that Algernon has taken on Merlin as his apprentice. She lets him into the secret about Tabby and together they hide him in the cabin of a small boat, and secretly supply him with food. Miss Hardbroom, while taking a walk on the beach, hears a cat mewing and goes to investigate. She slips on a kipper and is knocked unconscious. Meanwhile, Ethel and Drusilla have become suspicious of Mildred and after discovering the boat with Tabby on board, they untie the rope and send the the boat down river towards the rapids, completely unaware that Miss Hardbroom is on board...