Six months after their last mission, three members of the British special-ops Section 20 team--Gracie Novin, Samuel Wyatt and Thomas "Mac" McAllister--are reunited for what they think is a routine "cleanup" exercise in Malaysia. Things get complicated when their new commanding officer, a borderline burn-out named Alexander Coltrane, learns that a British operative, in possession of intel about a downed Russian plane, has been killed in Kuala Lumpur after meeting with a covert Russian operative, Katrina Zarkova. The trail leads Wyatt, Mac and Novin to a Russian safehouse where Katrina and her team of Russian soldiers are attempting to track a mysterious "package" stolen from the plane, which crashed into the ocean under suspicious circumstances. The confrontation gets bloody when members of a brutal Malaysian triad arrive, setting off a chain of dangerous encounters in the skies and skyscrapers of Kuala Lumpur.

Section 20 forges an uneasy alliance with Zarkova in hopes of tracking down a nuclear warhead in Kuala Lumpur. High Commissioner McKitterick finds himself in an untenable dilemma, while Novin defies Coltrane's orders to settle a score.

Section 20's search for the missing nuclear warhead leads them to Goa, India, where three scientists have been kidnapped. Section 20 infiltrates a suspicious fund-raiser as Coltrane and new S20 computer whiz deal with a breach in security.

The team is forced to lean on Zarkova to commandeer high-end Russian technology, crack the encryption code and make a final foray to a secret hideout, where Vartak, Gopan and the nuclear packages await.

Section 20 journeys to the Punchan Province and connects with a DEA agent with inside intel on Zaza and Dagon. Coltrane tasks Novin with impersonating the nuke buyer in order to ascertain the WMD's location.

After ditching the seaplane they hijacked, Novin and Zarkova find themselves at the mercy of corrupt police, while Mac and Wyatt take temporary refuge in a local village. Coltrane finally learns the location of the suitcase nukes, but the revelation comes at a high price. Finally, Section 20 tracks down Zaza and the nukes - as well as an unexpected interloper - in a remote compound, and all hell breaks loose. Expecting the worst, Wyatt makes a call back home, while Pavel forces Zarkova to come to terms with what happened to Alpha Group.

As Wyatt convalesces, Coltrane, Mac and Novin embark on a covert, 24-hour mission inside Russia to extract an FSB analyst with potentially vital information. Zarkova questions Pavel's true identity, but chooses to stand by her commanding officer. Tracking Hassan to an outpost in the Indonesian jungle, Section 20 ends up facing off with Pavel and Zarkova, as Chetri zeros in on the nuclear suitcase in a Jakarta mall.

Coltrane defends his decision to go rogue with S20. After tailing Hassan and the nuclear suitcase to a deserted shopping mall in Jakarta, Wyatt and Novin face down threats from Komodo soldiers and, later, Colonel Aldo and his insurgents. As Katrina weighs her allegiances, Pavel resets the parameters of the Russian plans to overthrow the Indonesian government.

In pursuit of Pavel, Section 20 clashes with two other Russian renegades, Natasha Petrenko and Artem Orlov, as they attempt to purchase sophisticated software designed to short-circuit a ghost satellite containing precious cargo. After a brief respite with his wife, Madison, Wyatt takes a temporary security job working for Caleb Montgomery, an obnoxious military-tech tycoon, but soon finds himself thrust back into the danger zone.

Section 20 faces an ultimate dilemma as it battles Pavel and his team of Russian turncoats for keys to Soviet-era missiles thought to have been destroyed years earlier. The conflict takes S20 from a remote village in the Philippines to Saloglu, Azerbaijan, where three long-range missiles are ready to be fired on major cities in the West. Can the team stop Pavel and save the world from Armageddon?