
Wikipedia
Someone is trying to kill Frank Moses again after a leaked document links him
and Marvin to Nightshade, an operation during the Cold War where the CIA
planted a nuclear bomb in Moscow. Hunted as terrorists by intelligence
agencies, they follow a lead to Paris to find The Frog, a man who sells
information; from him they get a clue that leads them to a secret MI6
detention facility holding Bailey, the scientist whe created the bomb. They
also team up with Russian agents who have a shared interest in locating the
bomb. They extract Bailey, who guides them to Moscow and locates the bomb.
There Bailey betrays them and takes the bomb (a small, undetectable red
mercury device much worse than a nuclear bomb) to deliver it to the Americans;
but Bailey's intention is to detonate the bomb, not sell it. When the
Americans attempt to double cross Bailey, he escapes and takes refuge in the
Iranian embassy in Londen. Our heroes flush him out and trick him into
escaping on a plane with the dissimulated bomb, that Bailey had alrealy
activated earlier. The bomb explodes over the sea, causing no harm.