Ruthless Vows is the epic conclusion to Rebecca Ross’s Letters of Enchantment duology, following Divine Rivals. The story continues the romance between Iris Winnow and Roman Kitt as they are caught in a devastating war between the gods Dacre and Enva. Iris and Attie return to the front to report on Dacre’s movements, while Roman, having lost his memories, finds himself trapped in Dacre’s realm.

As Roman begins communicating with a mysterious correspondent through an enchanted letter, he must decide where his loyalties lie. The novel combines fantasy, romance, magic, war, journalism, and an enemies-to-lovers relationship, bringing Iris and Roman’s story to its conclusion.