After killing her husband, Mei Foster meets with Shiro and his father, an aging boss of the Yakuza crime syndicate. Shiro kills the older man in a fit of rage, and at Mei's suggestion, he tells his people that Section 20 is responsible for the murder.
Locke authorizes an autopsy on Robin Foster's body. Scott and Stonebridge take Foster's former assistant Lawan into custody. Lawan admits to feeding North Korea's Office 39 information and confesses to Foster's murder almost immediately -- which Locke finds suspect. His suspicions are confirmed when he receives the pathology test results; he learns that Robin was poisoned and deduces that Mei murdered her husband. At that moment, the Section 20 crib is attacked. Lawan is shot and after she is killed, the team learns that Office 39 is in bed with the Yakuza.
Scott picks up his son Finn, who remains bitter over Scott walking out on him. Scott realizes his car is being pursued. Shots are fired and Scott drives the car off the road; allowing himself and Finn to flee into the jungle. Despite Scott's best efforts to evade pursuit, gunmen eventually surround the father and son.
Locke and Martinez go to the Foster residence to confront Mei. Martinez finds a hidden cupboard full of paperwork and cash. Mei and Locke face off and she escapes after threatening to poison Robin's daughter Chloe. Locke investigates Mei's past and learns she's a highly-trained operative on a secret mission. Section 20 decides to use the Yakuza to get to her. In their research, they learn that Shiro is preparing to step up as leader. The team ambushes a meeting between Shiro's right-hand man and the syndicate council. Section 20 learns the location of the private island where they believe Mei is hiding out.
Section 20 breaks up Shiro's meeting with the council. Stonebridge and Shiro face off; ultimately Shiro escapes and Stonebridge is left behind by his team. Richmond learns that the shipment Mei is planning to receive is not meth, but vanadium -- material used in nuclear weapons.