Lexi emerges more powerful and ruthless than ever. Tom and the 2nd Mass must work together with the Volm to hold off the invading Espheni forces in what becomes the bloodiest battle of the series.

As Gordon and Joe prepare to ship the Giant, a suspicious defect calls their partnership into question. Cameron takes her future into her own hands.

Walt seeks closure in his wife's murder and Henry's case; Branch is suspended but continues to investigate Jacob Nighthorse.

A special shipment of the first sample of plutonium arrives at The Hill – one that could change everything. With the future of his team up in the air, Frank knows that having some of the precious material could make all the difference. As Frank desperately tries to keep his team alive, he learns that Liao has been detained by a covert outside party. Liza helps Abby find creative ways to survive life on The Hill. As the wives grow closer, competition escalates between Frank and Charlie in the lab.

Langham observes Masters and Johnson exiting a hotel room and shares his suspicions with DePaul, who is forced to make plans for her work without Virginia's involvement. Meanwhile, Betty attempts to conceal her infertility from Gene; and Masters tries to bring Johnson aboard as his assistant only to be thwarted by the head of the hospital, who takes a prurient interest in Masters' study.

Go behind the fix and see how Lena got Tiny's paperwork so quickly in this companion webisode to episode 204.

With her investigation in full swing, Kate zeroes in on Mickey. Meanwhile, the appearance of Tiny, a former member of Sully's gang, jeopardizes Ed Cochran's career. Plus, Mr. Keith sends Mickey to work at a Mexican restaurant, Abby meets a new friend at the gun range and Bunchy encounters a potential love interest at the bike shop where he has gotten a job.

After picking up a distress call near Jamaica, Chandler and a small team stage a rescue attempt. But a surprise attack leave Chandler and Tex stranded at sea. Slattery and the crew search desperately to find their lost at sea Captain and his comrade, hoping to do so before their enemies beat them to it.

Nora takes care of some unfinished business in Mapleton before heading to New York for the Second Annual DROP conference (Departure Related Occupations and Practices). Agitated that her ID has been pinched, Nora, wearing a 'Guest' badge, scours the convention for her imposter, and ends up getting detoured by an amorous salesman, a best-selling author, and a rogue attendee.

Vanessa, Darius, and President Westwood deal with the hostage crisis. Alison and James make a strange discovery after testing Kyle that may lead to more questions than answers. The world reacts to news of the lottery as the U.S. government prepares to open the testing centers.

A secret autopsy demonstrates the bizarre progression of the mystery virus, prompting Jim to make a startling confession. Eph and Nora race to find the father of the youngest victim of the plane tragedy, but someone unexpected beats them to it. Ansel, in the grip of disease, takes desperate measures to protect his family.