Welcome to the most magical house in London. <br><br>The family of eleven-year-old twins Oz and Lily have inherited it, together with the mysterious shop downstairs. Long ago, the shop's famous chocolate-makers, who also happen to be Oz and Lily's great uncles, were clever sorcerers. Now evil villians are hunting for the secret of their greatest recipe. The terrifying powers of this magic chocolate have the ability to destroy the world. <br><br>Soon, Oz and Lily are swept into a thrilling battle, helped by an invisible cat, a talking rat, and the ghost of an elephant. It's up to them to stop the villians and keep the magical chocolate recipe out of harm's way. Their family and the world depends on it.