In a strange alternate world, where the British Empire is still a cruel ruling force, a young boy called Adam has uncovered something incredible in a rubbish dump in London - a mysterious, mythical animal. A Tyger. The Tyger is in danger, and Adam and his friend Zadie are determined to help. However, they soon realise it isn't just the Tyger's life at stake: the world they live in is also on the precipice of darkness. Luckily, the two children have great powers within them, and the Tyger can show them how to harness what's inside.