After a border ambush goes wrong, an Irish paramilitary, Michael, witnesses the shooting of his pregnant wife at the hands of an SAS sergeant Tempest. When Tempest is sent back to London to lead a covert counter-terrorist operation, Michael joins a ruthless active service unit (ASU) wreaking havoc in the capital. For Michael, the mission is personal – to hunt down Tempest – and he’ll stop at nothing to avenge his wife's death.