Merlin, the 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. He's 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. The circus is in town, and Merlin wishes he could appear as one of its stars. His collar works its magic, but no sooner is he in the big top than things begin to wrong. He plummets into the safety net from the trapeze, dives into an empty tub and is fired right through the roof from a cannon. Perhaps Sandybay is not so dull after all.