What We Did on Our Holiday is a hilarious journey through an unforgettable family holiday as a couple attempts to keep their impending divorce secret from their extended family, Doug (David Tennant) Abi (Rosamund Pike) and their three children travel to the Scottish Highlands for Doug's father Gordie's (Billy Connolly) birthday party, where its soon clear that when it comes to keeping their divorce under wraps their children are their biggest liability.

From nine year old Lottie's notebook to keep track of the lies so she remembers which ones to tell, to four year old Jess's perverse attachment to a brick named Norman, for their parents a week has never seemed such a long time. But its middle child Mickey and his granddad's shared passion for Vikings which gives rise to the most far-reaching and unexpected consequences. When a day at the beach turns to tragedy, the children take matters into their own hands.