Seconds before the Earth is demolished to make way for a galactic freeway, Arthur Dent is plucked off the planet by his friend Ford Prefect, a researcher for the revised edition of The Hitchhiker's Guide to the Galaxy who, for the last 15 years, has been posing as an out-of-work actor.

There is a long tradition of Great Detectives, and Dirk Gently does not belong to it. But his search for a missing cat uncovers a ghost, a time traveler, AND the devastating secret of humankind! Detective Gently's bill for saving the human race from extinction: NO CHARGE.

The hugely powerful Key to Time has been split into six segments, all of which have been disguised and hidden throughout time and space. Now the even more powerful White Guardian wants the Doctor to find the pieces. With the first segment successfully retrieved, the Doctor, Romana and K9 trace the second segment of the Key to the planet Calufrax. But when they arrive at exactly the right point in space, they find themselves on exactly the wrong planet - Zanak.