He must never touch the hands of the clock. He must master his anger. He must never, ever fall in love.

Jack and the Cuckoo-Clock Heart

In Scotland 1874, Jack is born on the coldest day ever. Because of the extreme cold, his heart stops beating. The responsible midwife in Edinburgh finds a way to save him by replacing his heart with a clock. So he lives and remains under the midwife's protective care. But he must not get angry or excited because that endangers his life by causing his clock to stop working. Worse than that, when he grows up, he has to face the fact he cannot fall in love because that too could stop his delicate heart.