Sara and Greg are quarantined after responding to a crime scene that’s contaminated with a deadly pathogen.
Liv becomes friends with a Korean pop star after she visits America to study Liv’s acting for the Korean version of the hit show, “Sing It Loud.”
When a motorcade detail is delayed, it leads to a wacky competition, and Charles must get an incriminating videotape from Hitchcock.
Sarah Bunting continues to cause waves above stairs, but this time she may have gone too far. On returning to Downton, Thomas suffers an inexplicable illness and Baxter suspects there’s more to it than he’s letting on. Violet reveals to Isobel the surprising truth of her past with Prince Kuragin. Mary comes to a decision concerning Lord Gillingham, but things don’t go quite as planned. When Rose’s father returns to Downton, he breaks news that will shock the whole family.
Akley becomes vulnerable when he tries to fix Thin Man's shortcomings.
Frank and Caterina have to rescue her ex-fiancé, Zac, from a Mauritanian warlord. However Zac won't leave unless they can take a bus load of orphans that he has been caring for with them.
Carrie is forced to intervene when Fara fails to recruit a key asset. Still reeling over events in Islamabad, Quinn zeroes in on a potential lead.
Eli asks a respected campaign manager to help Alicia explore the option of running for state's attorney.
Marian falls under a freezing curse and the townspeople believe that Elsa is responsible. When Emma and David go to Robin's camp to look for clues, they find Will Scarlet, who leads them to the culprit. Meanwhile, in the Arendelle of the past, Elsa and Kristoff go to find the urn that Hans plans to use to imprison Elsa, and encounter the Snow Queen.
Spring arrives and things start plunging through the ice. The wardens investigate a case of injured bald eagles. A sled sinks into a partially frozen river under suspicious circumstances. A deer carcass has the wardens searching for a poacher.
A group of erstwhile members of the Brokenwood Golf Club, committee members no less, have gathered for their regular Wednesday morning round. They are playing their approaches to the first green when a zombie-like figure lurches from the early-morning gloom, coming towards them. It takes the golfers a moment or two (apparently) to realise this is actually Adele Stone, the Club owner - her face red and blistering; gasping desperately for breath. Then she falls from sight, into a greenside bunker. By the time the guys get to her, Ms Stone is very much dead. And so Mike and Kristin are called to investigate what appears to be homicide by poisoning.
We learn the true motives of the Terminans as Rick and the group find themselves in a vulnerable situation.
Emily's life is on the line as Victoria orchestrates a family reunion with deadly potential, regardless of who gets caught in the crossfire.
Noah escapes the city with his family to a Long Island estate. Alison and her husband struggle to move past a tragedy. Noah and Alison meet in a chance encounter.
While Elizabeth works to successfully broker a peace treaty between China and Japan, a Chinese student seeking political asylum threatens the deal. Meanwhile, tensions rise at home between Alison and Stevie during Alison's sleepover party.
Ange is exiled to Arzenal, and joins a group of Normas to become a soldier. Reluctant from the start, she must adapt and realize she no longer is a princess.