An ordinary British family contends with the hopes, anxieties and joys of an uncertain future in this six-part limited series that begins in 2019 and propels the characters 15 years forward into an unstable world. Daniel (the youngest brother) is getting married to Ralph, Stephen (the oldest brother) and Celeste (his wife) worry about their two daughters, Edith (the oldest sister) is engaged in one humanitarian cause after another, and Rosie (the youngest sister) is a single mother with spina bifida raising one boy, and about to give birth to a second. Presiding over them is Gran, the imperious Muriel.
In 2026, the banking crisis has led to a recession. Viv Rook proposes a national IQ test, with anybody with an IQ of less than 70 being barred from voting. Ukrainian police come to arrest Viktor, but he narrowly escapes. Ukraine has now criminalised homosexuality, so Viktor decides to enter an LGBT-friendly country illegally and claim asylum. Edith has returned to activism, infiltrating the offices of a corporation with links to the Syrian dictatorship under an assumed identity, using Lincoln as part of her cover. The information she steals is released, causing a scandal that shuts down the corporation. Bethany makes friends with Lizzie, another "tran-shuman" teen at her workplace. The availability of self-heating ready meals leaves Rosie redundant from her job. Viktor claims asylum in Spain and Daniel visits him there. Stephen now works as a bicycle courier, among other low-paid jobs, and begins an affair with co-worker Elaine. Celeste finds out, but does not confront him. The Lyons siblings' estranged father dies from antibiotic-resistant sepsis after being struck by a courier's bicycle. The siblings attend his Water Burial to support Stephen, who is the only one who really cares. There they meet with "Steven with a V", their father's son by his second wife Jacqueline, whom all the Lyons children despise. Rosie tells Edith she has always believed her father left the family because he couldn't deal with a child in a wheelchair. Bethany and Lizzie secretly travel to Liverpool for black-market cybernetic surgery, using 10,000 pounds Stephen gave her for her 18th birthday. Bethany calls her mother in hysterics; Lizzie has been given a bogus, malfunctioning eye implant, but Bethany escapes unharmed. At first Celeste is just glad Bethany is safe, but later she is furious that Bethany wasted money when the family is in financial crisis. A general election gives The Four Star Party fifteen seats in a hung parliament, allowing Viv Rook to determine the balance of power between a minority government and the opposition. Hearing the election results, Stephen uses the car he rented for the funeral to run over a fellow courier's bicycle in a fit of frustrated rage, while his siblings sit impassively in the passenger seats.