With the publication of The Restaurant at the End of the Universe Douglas Adams had completed his novelisations of the two Hitchhikers Guide to the Galaxy radio series, and the story had effectively reached it's natural conclusion, with the wrapping up of all the major plot-threads concerning the quest for the Ultimate Question, the destruction of planet Earth, and Zaphod's theft of the Heart of Gold. The series popularity though resulted in Adams bringing out a third Hitchhiker's book, with the main storyline being recycled from an unused Doctor Who storyline he had written called Doctor Who And The Krikkitmen.
As such this novel feels a little strained at times in bringing all the original Hitchhiker's cast back for a third outing, with Arthur Dent and Ford Prefect's idyllic prehistoric life at the end of The Restaurant at the End of the Universe transformed into a nightmare they can be rescued from, and Marvin having his death in the previous book undone. By far the biggest change though is Slartifartbast, who has changed from an eccentric planet designer into the main plot-driver of the book, essentially taking over the Doctor's role as would be saviour of the universe and guardian of the timelines, with his new background in the Campaign For Real Time replacing the role of Doctor Who's Time Lords.
However, the odd strained moments are more than offset but the typically brilliant concepts on display - including the Hitchhiker's art of flying by throwing oneself at the ground and missing, Slartifartbast's Bistromathematical spaceship, and the re-acquaintance of the sentient bowl of petunias from Hitchhikers Guide to the Galaxy that results in Arthur Dent glimpsing his own future.
Not quite up to the standard of the first two books in the series, Life, the Universe and Everything is nevertheless clever enough and funny enough to be essential for fans of the earlier novels.