Section 20 are called into Bangkok, Thailand to rescue Chloe Foster, the daughter to British ambassador and longtim friend of Phillip Locke (Green), Robin Foster (Tim McInnerny). The team find the compound where she is being held, but during the raid the kidnappers escape with Chloe. After identifying the lead kidnapper as Ray McQueen (Max Beesley), Michael Stonebridge (Winchester), Damien Scott (Stapleton) and Julia Richmond (Lukes) track him to a nightclub and plant a tracker on him. However, McQueen soon realises he is being tailed and tries to escape with Chloe again, while also contacting Foster to deliver an armed bomb to the embassy where he is negoatiating with the North Koreans. With less than fifteen minutes, Scott and Stonebridge have to find McQueen and contend with a local gang. They ultimately rescue Chloe and apprehend McQueen, but Locke fails to stop Foster before the bomb detonated, killing Foster and a North Korean general

在享受一个难得的假期之后，Scott（Sullivan Stapleton）和Stonebridge（Philip Winchester）被召回20分部接受新的任务。另一名20分部特工在黎巴嫩贝鲁特追踪高深莫测的恐怖分子al-Zuhari不幸丧命，Scott和Stonebridge必须查清事情的真相。一条新线索引导他们来到哥伦比亚的偏僻丛林——拒信al-Zuhari的一个盟友正潜藏在这片由势力庞大的贩毒集团控制的地区。 Rhona Mitra将继续在本季扮演Rachel Dalton少校，Michelle Lukes扮演Julia Richmond中士，Liam Garrigan扮演Liam Baxter中士。 本季新加盟的演员包括：Robson Green扮演Philip Locke上校；Dougray Scott扮演叛逆特工James Leatherby；Milauna Jackson扮演反恐行动组在执行任务过程中遇到的关键人物Kim Martinez；Zubin Varla扮演神秘的可疑对象Leo Kamali。

The Great War is over and a long-awaited engagement is on, but all is not tranquil at Downton Abbey as wrenching social changes, romantic intrigues, and personal crises grip the majestic English country estate. As other great houses are crippled psychologically and financially in the wake of World War I, Robert, Earl of Grantham, sticks to his duty to maintain Downton more firmly than ever. But in this changing landscape nothing is assured, and could it be that even the war-weary Crawleys must fight a new battle to safeguard their beloved Downton? 

The Great War rages across Europe, and not even the serene Yorkshire countryside is free from its effects. The men and women of Downton are doing their part both on the front lines and the home front, but the intensity of war only serves to inflame the more familiar passions: love, loss, blackmail, and betrayal.

Lord Robert Crawley and his family live a life of leisure, while a fleet of servants, including butler Carson, attend to their every need. But two events conspire to shake things up: the sinking of the Titanic, which claims Crawley's heirs, and the return of his valet, Bates. Since Crawley and Lady Cora have three daughters, his distant solicitor cousin, Matthew, becomes heir to the estate. With that, the scheming begins, since Thomas the footman views Bates as an interloper and Crawley's mother, Violet, feels the same way about Matthew's mother, Isobel.

When a chance encounter brings soldier John Watson into Sherlock's life, it's apparent the two men couldn't be more different, but Sherlock's intellect coupled with John's pragmatism soon forges an unbreakable alliance as they investigate a series of baffling cases together.