Port Stanley has a feature that no other town on earth has; its own sea monster. Bessie lives in a cave on the other side of Picnic Hill and calls Lake Erie her home. Hidden from those who would harm her, yet close enough that her two keepers can come to her aid when she's in danger. Mason Brooks didn't realize that he was one of them until he met the man some would call the devil. Mason had inherited the ring, known as the bloodstone, from his father. He had never been told about the powers it had or about the connection to Bessie.
Black Tom wears the second ring, called the sky ring. His sudden appearance keeps the people on edge, for there is no record of him prior to this summer. It soon becomes clear that Tom is mistreating Bessie, giving her meat when she's a vegetarian and injecting her with powerful drugs. There are several deaths out on the lake which Bessie is being blamed for. But no one can blame her for the murders that take place on Picnic Hill. Mason suspects Tom. Yet Tom knows how to beat the system and is never convicted of any of them. And Mason has to prove one thing...that Black Tom is not his brother.
The two rings need to work in harmony in order to keep Bessie alive. She eats the algae that grow in the lake and helps to balance the ecosystem. If she doesn't die a natural death Lake Erie will perish.