Ottilie Zhang has flourished since her escape from the clutches of China Jane. Her greatest joy is combing the Thames foreshore with Joe, looking for treasure During one mudlarking expedition, she uncovers something astounding and troubling: a golden Aztec skull, once the property of a legendary pirate. It comes with a grim reputation. Ottilie’s hard-won happiness is threatened when China Jane once again tracks her down, offering an impossible choice: hand over the skull, together with a golden skeletal hand that once accompanied it, or Jane will order the deaths of her cherished friends, one by one. With only days to complete the task, Ottilie turns to fledging suffragette Adelaide Bing for help, encountering obstacles both human and ghostly as she fights against time itself to save her friends.