The main story arc of the series focused on the significance of the character of Clara, whom the Doctor had encountered twice before as Oswin in "Asylum of the Daleks" and as a governess in "The Snowmen". It also features the recurring appearance of the Doctor's enemy, The Great Intelligence.
United is based on the true story of Manchester United's legendary "Busby Babes", the youngest side ever to win the Football League and the 1958 Munich Air Crash that claimed eight of the their number. The film draws on first-hand interviews with the survivors and their families to tell the inspirational story of a team and community overcoming terrible tragedy.