'I heard a murder being planned.' Scarper Jack is a chimney-sweep's boy and he's actually in a chimney when he hears two voices planning a murder.

He knows where and when it's going to happen - but there's no way he can stop it.

With the help of two unexpected friends - a posh boy and a sewer rat of a girl - he sets out to solve the mystery and track down the murderer.

Only to find that it can be dangerous to know too much...