Harry is desperate to clear his name after being implicated in Loxley's dubious business dealings. Victor and Agnes endure some agonising soul-searching when a loved one returns, and Miss Mardle is forced to grapple with a romantic dilemma. Lady Mae takes a big risk on Harry's behalf - one which pays off - but he is stopped dead in his tracks when Rose brings news that shatters his world forever.

Having endured a scandal in the press and dealt with Henri's arrest, Harry is determined to get the store back on track and asks Delphine to organise a special event, but takes a risk by inviting notorious American journalist Winifred Bonfils Black. Meanwhile, as Miss Mardle experiences true happiness, Agnes doubts she has made the right choice, and Lady Mae and Frank unite to help Mr Selfridge, but could there be more trouble on the horizon?

Tempers flare as Harry and Loxley face off, Miss Mardle gives Mr. Grove a tongue-lashing, Victor and Henri clash, Kitty tells Frank to shape up, and Delphine finds her influence wavering. Meanwhile, an American journalist searches for the happy side of Selfridges, the store promotes "the comforts of home," Agnes gets her fifteen minutes of fame, Mr. Grove gets a long-sought heir, and Lady Mae manages to save the day.

Harry returns, making a revelation concerning the press rumors surrounding his absence. Delphine creates a stir by arranging a spending spree by Keystone Studios head Mack Sennett, his biggest star, Mabel Normand, and a bevy of Sennett bathing beauties, who are all on a junket to London. Meanwhile, Henri is spared a legal dilemma only to land in a romantic one. Miss Mardle also faces a love quandry, and Lady Mae has trouble exiting from her miserable marriage.

Discussing Harry's mysterious disappearance on a business trip to the Continent, Kitty tells Frank: "It's like he's vanished into thin air!" During the chief's absence, Henri lands in trouble, one of the staff is killed at the front, Josie finds unexpected joy, and Frank publishes a shocking scandal. As if that isn't enough, Rose faces a falling out with those close to her, and bad news arrives about another soldier on the staff.

Business carries on at Selfridges, where German-made goods are being replaced with English products. Harry organizes a patriotic concert to benefit the troops, featuring a popular music hall tenor (portrayed by Alfie Boe) who gets Lady Mae (his former stage partner) to join him. Miss Mardle's new lodger, a Belgian violinist, also participates in the concert, raising some eyebrows. Amid the festivities, a complex drama unfolds that sets the future course of events for Henri and Harry—all while the unsuspecting audience sings "It's a Long Way to Tipperary." It's a very long way indeed.

Young Englishmen are off to war, and Harry's son, Gordon, is itching to enlist. Only fifteen, he is assigned to man the tea counter at the store instead. Harry is also itching to do something war-related and angles for a spot on the government's military procurement committee. This leads to a high-stakes poker game, pitting the canny American against none other than Lord Loxley, who aims to give "that Yank the trouncing of his life!" Meanwhile, Miss Mardle has invited Agnes to share her new home and welcomes a Belgian refugee as well. Mr. Thackeray, head of fashion, gives himself a special war assignment: get to the bottom of Henri's suspicious behavior!

It's August 1914, and Britain is now at war with Germany. Expecting the great adventure to be over by Christmas, young men flock to enlist, including a large contingent of Selfridges staff. Though an American himself, Harry rises to the occasion, promising the men their jobs when they return and hosting a benefit for victims of the German invasion of Belgium. Mr. Grove shocks Mr. Crabb with a bold strategy for meeting the store's manpower needs. Lord Loxley's plot deepens. And Henri gets deeper into a mysterious transaction.

"Empire Week" at Selfridges symbolizes all that Britain has to fight for, and it's up to Agnes to create displays that evoke every corner of the realm. Overwhelmed, she gets unexpected help. Meanwhile, Harry gets an unexpected visit from Lord Loxley, who is suspiciously civil and offers to line up a celebrity guest for the celebration. But he wants advice from Harry in return. Mr. Crabb calls on American know-how to help Mr. Grove keep his job. Frank has a date with Kitty. Miss Mardle makes a startling revelation. And all await Mr. Churchill's arrival at the store…

Once considered the vulgar venture of an upstart American, Selfridge & Co. is now the toast of London, about to celebrate its fifth anniversary. The store's staff plans a surprise for Harry, and unexpected guests show up. Meanwhile, the latest sensation is a new nightclub, run by libertine Delphine Day, who is a new friend of Harry's wife, Rose. Are the two institutions—Selfridges and Delphine's—destined to cross paths? In other action, Lady Mae's husband, Lord Loxley, is back in her life again. Rose spots a ghostly but familiar face at Delphine's. And Agnes gets a huge promotion but makes a bitter enemy. On the larger stage, the Archduke of Austria is assassinated, touching off a crisis on the Continent.