This is the debut adventure of Bernice "Benny" Summerfield, one of the more memorable companions of Who spinoff fiction - future archaeologist, hard drinker, unsuccessful lover, heroine of numerous spinoff books and audio plays in her own right. The Seventh Doctor and Ace arrive to explore the planet of Heaven; Ace falls in love with a Celtic crusty; the Doctor has difficulty distinguishing her from Susan and, of all past companions to pick, Dodo; and religious cults and various other locals and visitors are dealing, whether they know it or not, with a horrible intelligent fungus which is infecting their bodies.
Quite apart from Benny, whose debut is as memorable as I hoped it would be, this is a good novel for Ace, whose doomed love affair, recollections of her youth in Perivale, and tentative renegotiation of her relationship with the Doctor combine to make her much more interesting and compelling here than she ever was on screen. Some of the familiar Paul Cornell motifs are here - people trapped in a church or local equivalent; owls - but there are some very pleasing nods to the space opera future portrayed in Pertwee-era Who (the Draconians; the IMC) and the planet itself, and the gruesome invasive fungoids, are convincingly attention-grabbing. One of the better New Adventures, I suspect (not that I have read many of them).