Swept into the bright hustle and bustle of New York, Lily, Robert and Malkin discover shadowy secrets lie beneath its surface. For there are chilling goings-on in their hotel…

A strange boy held captive, haunted by an undersea mystery; and a revengeful villain with a treacherous plan.

Searching for clues, Robert and Lily are plunged into deep water… But can they reveal the deadly truth before the secrets submerge them?

Join Lily, Robert and Malkin on a fantastic voyage of terror and triumph, in the fourth and final Cogheart Adventure…