In contemporary 1980s New York, there is a secret society of immortals who have been fighting each other for centuries, guided by the singular rule that only decapitation can kill them. The immortals aspire to win "The Prize" which comes with untold power and knowledge, achievable only when one remains. The protagonist, born in the Scottish Highlands in the 16th century, is one of these immortals. After living through the ages under various identities, he now works as an antique dealer in New York City. His peaceful existence is shattered when he becomes embroiled in a deadly game with other immortals, a game that has finally drawn to its end as few of them are left.

The protagonist's life story is interwoven with flashbacks that explore his past, including his first death and subsequent realization of his immortality, under the mentorship of another, more flamboyant immortal who teaches him the ways of their kind. As he learns about the rules and the stakes of the ongoing war between immortals, he forges deep bonds, faces betrayal, and experiences great love and loss. Meanwhile, in the present day, a menacing and powerful immortal foe is killing off the remaining immortals, seeking to be the last one and claim The Prize, forcing the protagonist to confront his destiny and the weight of centuries of existence as the battle moves inexorably towards its final confrontation.