The Doctor receives a mysterious message in a package that has come from Kerblam, the largest retail company in the galaxy. Sensing something suspicious lurking behind the company's cheerful facade, the Doctor, Graham, Ryan and Yaz take on an undercover investigation at the Kerblam warehouse - a vast storage space that takes up an entire moon.

Julie Hesmondhalgh (Coronation Street, Broadchurch) and Lee Mack (Not Going Out) guest star alongside Jodie Whittaker, Bradley Walsh, Tosin Cole and Mandip Gill.