 Doug McLeod (David Tennant) and his wife Abi (Rosamund Pike) unite following a tense separation to travel to the Scottish Highlands for Doug's father Gordie's (Billy Connolly) 75th birthday.Gordie has terminal cancer so Doug's brother, millionaire Gavin McLeod (Ben Miller) has arranged a lavish party for him, inviting all the important people in the neighbourhood.Despite difficulties getting their three children, Lottie (Emilia Jones), Mickey (Bobby Smalldridge), and Jess (Harriet Turnbull), to leave the house, they hit the road, but find it congested and they are forced to stop overnight.