Andromache of Scythia (“Andy”), Booker, Joe, and Nicky are centuries-old warriors with unexplained regenerative healing abilities who use their vast experience to work as mercenaries, taking missions to help people. Breaking their rule of never working for the same employer twice, they accept a job from former CIA operative James Copley to rescue a group of kidnapped girls in South Sudan.
During the mission, which proves to be a ruse, they are ambushed and killed. After quickly recovering and killing their attackers, they realize that Copley set them up to remotely film their regeneration.
Meanwhile, in Afghanistan, U.S. Marine Nile Freeman has her throat slit while taking down a military target during a house search, only to recover without a scratch. Later, she shares a disturbing dream with the other immortals, who are then alerted to her existence, as they experience dreams of any new immortals until found. Andy tracks down a confused Nile and extracts her from Afghanistan before military personnel can transfer her for further testing.
Copley shows the video of the ambush to pharmaceutical executive Steven Merrick, who sends operatives to capture the team. Andy brings Nile to a safe house in France, where she meets the rest of their team.
The group shares some of their past and reveal that they are not truly immortal: their ability to heal eventually stops, without warning, which happened to a previous immortal, Lykon. She is also told about the female immortal Quynh, the first of Andy’s comrades, who was captured, accused of witchcraft, and lost to them when cast somewhere into the sea in an iron maiden, and has been continually drowning ever since.
