A deadly subway collision is investigated as a New York City medical examiner attempts to discover the truth behind his inexplicable immortality.
When a crisis at LAX prevents dozens of airplanes from landing, the government brings in a group of misfit geniuses to sort things out.
Having won 100 denari each through Stylax's betting on a chariot race, he and Marcus have very different ideas on how to spend the money. Marcus, naturally, wants to spend it on Cynthia, whilst Stylax prefers a more laddish approach.
Henry sets out to find the Gehenna Key, which will allow his master Moloch to escape from Purgatory with an army of the damned. Meanwhile, Ichabod tries to free himself from his buried tomb, and Jenny must escape the Hessians holding her on Henry's behalf.
After Ned and Jesse Banks publish a video of a mysterious outback accident that involved a couple of teenagers and a lorry from a classified research facility, they then have to deal with a political machine that is desperate to keep the truth hidden.
Austin disappears before his performance on "Video Countdown Live"; the group finds out that Brooke is holding him hostage until he writes her a song.
Vanessa confronts Darius about his plans and surprises him by trying to subvert them. Meanwhile, Allison and Kyle meet the MayTwos and learn they are funded by a powerful sponsor who can help rescue Elvis and the president learns about Gabrielle's deal with Perry and confronts her about her motives.
Joanna, Freya and Wendy revisit one of their former lives. Dash's one night stand turns out to be somebody better than expected. Ingrid attempts to bond with her grandfather.
Honora Bowen and Matt Strutzel survive hunger and dehydration in Brazil's North Region. Despite Honora passed out from severe heat, Matt completes the challenge all alone.
Setrakian leads Eph, Fet and Nora in the hunt for the Master’s lair. Left behind at the pawnshop with Mariela, Zack risks his safety for Mariela's sake.
The story moves on to 1924, when the first ever Labour government heralds a sea change that is felt throughout the nation - nowhere more so than at Downton. A suggested plan for a war memorial unexpectedly pits Carson against Robert and Mrs Hughes. Young Jimmy the footman is the object of some unwanted female attention. Thomas gives Baxter an ultimatum. Branson's growing friendship with someone Robert considers quite unsuitable causes concern. After the tragedy she has been through, Lady Mary now seems ready to find love once more. Cracks appear in Edith and Tim Drewe's special arrangement as she struggles to keep her emotions in check - something which may have disastrous consequences for the entire household.
Chalky heads in a new direction; Margaret finds herself in a quandary; Nucky hosts a prospective partner from Boston; Luciano and Siegel meet with Narcisse in Harlem; in 1884, young Nucky flirts with a girl.
Ray prepares in case he's arrested. Mickey's heist doesn't go as planned.
It seems that everyone is moving... literally; Stephan and Allyce finally get married; Pike Mike plans on moving to a quieter part of the lake; Randy gets his cabin-sized raft stuck on a sheet of ice in the river.
A female army medic struggles to prove herself while on assignment in Afghanistan.
A television crew arrives at the clinic to document Masters and Johnson's work treating sexual dysfunction. Masters considers the publicity premature, and himself unsuitable as a television presence. Virginia deals with the fallout of having prioritized her work over her parenting when George argues to take their children on a trip with his new wife. Plus, Libby finds in Robert an appreciation for what she has to offer. And Langham realizes there's no way out of his sexual contract with Flo.