Edinburgh, 1874. On the coldest night the world has ever seen, Little Jack is born with a frozen heart and immediately undergoes a life-saving operation. But Dr Madeleine is no conventional medic and surgically implants a cuckoo-clock into his chest. Little Jack grows up different to other children: every day begins with a daily wind-up. At school he is bullied for his ticking, but Dr Madeleine reminds him he must resist strong emotion: anger is far too dangerous for his cuckoo-clock heart. So when the beautiful young street-singer, Miss Acacia, appears - pursued by Joe, the school bully - Jack is in danger of more than just falling in love...he is putting his life on the line.