Christmas 2010: Jo Grant finds herself stuck in a department store elevator with an alien creature called Huxley. Huxley is a narrator from Verbatim Six. He is here to let Jo revisit the best time of her life — when she was the plucky companion to that eccentric Space/Time traveller known only as... Iris Wildthyme. Confronted with memories she knows nothing about, Jo agrees to a meeting with Iris inside her transdimensional bus. Together the three of them take a trip back in time: back to the 1970s, to UNIT HQ and a meeting with the only person who knows the whole truth...