After a series of death threats by a group of rival mudlarkers, Barnaby and Winter are drawn into a complex murder investigation. A jar containing human remains points to a heated treasure hunt dispute that turned deadly.

When a booby-trapped cuckoo clock kills a guest at Godley Manor's engagement party and turns the celebration into chaos, Barnaby and Winter must uncover a web of hidden pasts, family feuds, and ticking secrets before the killer strikes again.