Two FBI agents-Grant Mercer, a field-hardened Marine with scars he doesn't show, and Maya Voss, a brilliant but guarded profiler-are thrown together to hunt a serial killer obsessed with ritualistic murders based on ancient Roman rites. As they clash professionally and emotionally, the case turns personal when Maya becomes the killer's next target. Their pursuit uncovers a chilling conspiracy that leads Maya back to her own buried trauma-the disappearance of her twin sister, Eliza.

When Eliza resurfaces as part of a cult that sees Maya as the final offering, Grant races against time to save her. Together, they unravel a dark web of obsession, grief, and twisted devotion-and discover that sometimes, love is the bravest ritual of all.