Heathcliff and the Catillac Cats

Mungo's Dilemma [Catillac Cats] (1x56)

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Riff Raff sees a picture of a cat that looks like Mungo in the paper for which a reward is offered. The cats turn Mungo in and collect the reward, only to find they have left their friend in the clutches of a mad scientist. A rescue plan saves Mungo just in the nick of time.