Frank Moses, one of the most dangerous retired government operatives alive, has tried to leave his violent past behind him, settling in a normal live with his girlfriend Sarah. He's approached in a Costco by former cohort Marvin, who believes that someone is trying to kill them again. Frank dismisses him, but soon Marvin's car explodes. At Marvin's funeral, a slew of government workers take him to a secret location to be interrogated. While there, a man named Jack appears, kills the government agents, and threatens to torture Sarah if Frank doesn't cooperate with his every request. Frank escapes, thanks to Sarah and Marvin, who had faked his death to avoid suspicion. Marvin explains that they were listed as operatives in a Cold War-era mission called Nightshade, which involved moving a nuclear weapon into Russia. Jack is looking for the nuke, and he puts out into the world that Frank and Marvin have become rogue terrorists, looking to detonate a nuke. Their friend Victoria lets them know that she has received a contract to kill them. While on the run, they hunt down people who can lead them to Nightshade, eventually leading them to Dr. Bailey, a physicist slowly driven insane by being held in an asylum for over three decades. They must interpret Bailey's lunatic ramblings in order to find the bomb before it can be used to claim innocent lives.