During a school field trip to a historic mansion, thirteen-year-old Kofi is paired with Gavin, the class bully. Kofi hasn't yet made any friends at St. Mike's and rumours have spread about his suspension from Jameson, an elite private school. To ease his transition, Kofi's grandmother gives him an ancient amulet to wear for protection. Yet Gavin continues to torment him with racist taunts, and Kofi is almost relieved when Gavin misses the bus back to school.
Over time, Gavin's disappearance starts to weigh on Kofi's conscience. His big sister Esi has advised Kofi to keep his head down if he wants to succeed at his new school. But Kofi wonders if he should tell someone that he saw Gavin steal a book from the mansion's library-or that that same book later turned up in the garden with blood smeared on its pages.
When he's wearing the amulet, strange things happen. Kofi sees ghosts, hears voices from the past, and discovers he has second sight-a trait inherited from his Ghanaian grandmother. That's why Kofi can see the urisk, a river-dwelling creature who admits they traded Gavin to resurrect a long-dead friend.
If he wants to save Gavin, Kofi must enter another realm and make his own deal with the powerful Water Mother. But the only thing Kofi has that the goddess wants is the powerful amulet intended for his protection. Is a racist bully worth such a sacrifice?