Merlin, a mischievous black Labrador puppy, is thrust into an enchanted world where all his make-believe and playful dreams become a reality thanks to his magical red collar. Merlin, who has a nose for trouble, is joined in his wild adventures by his glamorous canine friend Kizzie and other inhabitants of Sandybay Harbour, including the lazy hedgehog Reg The Hedge; Gull, the surly seagull and Oscar the smart ginger cat who takes every opportunity to land Merlin in heaps of trouble. Merlin's kennel is in a mess and Ernie is not pleased. Merlin is instructed to clean up. After all, 'A man's home is his castle'. Now there's a thought. If Merlin were the king of his own castle then he could boss everyone about and be allowed to do whatever he wants. Time for his magic collar to do its thing. In a flash, Merlin is a king in his own castle. But the gloss begins to wear off: he receives complaints from the farmers - no rain is causing chaos to their plants; King Fido in the next kingdom wants to go into battle unless Merlin hands over his sausages and his favourite ball and, worst of all, he is informed that, as King, he is required to have a Queen! Maybe cleaning his kennel is not such a chore after all.