One of John's old nemeses, terrorist Malik Ahmad, steals an arsenal of nuclear warheads and a scientist to activate them. John is forced to work with his enemy Olga Petrovka in order to destroy them and rescue the scientist. Meanwhile, Natalie and Malcolm endeavor to protect John's identity from an FBI investigation.

The cabal trail leads John to a lawless Mexican town, where he is drawn into a deadly feud between the local drug lord, nicknamed El Diablo, and the town's police chief, Luna. At the same time, Natalie probes into a romantic connection between her late husband, Steven, and the fiancé of her political adversary, Speaker of the House Miles Latham.