Once upon a time I had an encyclopaedic memory of the plot of every book I owned and a goodly number that I didn't. These days I can barely remember the plot of books I read last year. I have absolutely zero recollection of the plot of the above. It is the first Past Doctor Adventure on my shelves so I deduce it features the First Doctor, Ian, Barbara and Susan. I like the 1950s vibe of the cover. I've just read the back cover blurb and I still remember nothing, though it, together with the cover make me think of When Worlds Collide.