Edinburgh, late nineteenth century. Little Jack is born on a day so cold that his heart remains frozen. Madeleine the midwife replaces his heart with a cuckoo-clock. It will work, as long as Jack follows the rules, mainly not falling in love. But his encounter with a fiery-eyed girl singing on a street corner and his decision to chase after her will test the resistance of his makeshift heart to the breaking point.

Chev Chelios returns to track down a ruthless Chinese mobster who has stolen his most prized possession: his heart. As he hunts down his enemy in Los Angeles, his battery-operated ticker requires regular jolts of electricity in order to work. Chev is determined to get his real heart back and wreak vengeance on whoever stole it.