After the events of Under a Dark Sky, Asher Perez has been hunting and killing immortals for years. Then one day, they contact him with a proposition. They need his help. An agent has gone missing on the Goliath homeworld, Nifelheim. Baseline humans are not welcome on the icy moon, and the only way for the team to get clearance is for Perez to talk to his old friend, Thorfinn Wagner: the heir to the Throne of Shields. Intrigued, Perez agrees to join them. But when civil war breaks out on Nifelheim shortly after they land, Perez realises there is much more to the story than he first thought. Something on Nifelheim wants them all dead.