A year after Russian mobster Mikhail Zakharov sent a team to England to kidnap Markus, an action that led to the death of Saffy - his adoptive sister Pope, and ex-soldier Barney travel to Moscow seeking bloody vengeance only for Markus to be saved by a mysterious stranger known only as Alpha.
When Barney's old SAS comrade "Smiler" Campbell arrives, the truth emerges: Colonel Oliver Hooper's black-ops facility at Portford created Alpha – an unwise experiment that went catastrophically wrong. The military now need Markus and Pope's monster-hunting expertise to track Alpha down, but does Smiler know more about Markus's true nature than he's letting on?
Markus, Pope and Barney are reluctantly drawn into a deadly alliance with the very military that may want to put Markus in a cage. With Alpha manipulating Markus toward darkness, Hooper closing in, and trust crumbling on all sides, the trio faces enemies on every front - and the greatest threat may be the monster growing inside Markus himself.