You might think that this book, like the fourth volume of he Hitch-hiker's Guide to the Galaxy, redefines the word "trilogy"; it does not. It is the sequel to Titus alone which is itself so different to the first two Gormenghast books that it is better to see the whole work as a pair of two-part novels.
Peake set himself a problem when he killed off all his most interesting characters by the end of the second book. Without Steerpike, Barquentine, Fuscia and Flay it must have been hard to see how the Castle could sustain another book so the only option was for Titus to leave and find more characters in the world outside to carry the story that his own somewhat un-likeable character was hardly up to. Muzzlehatch filled the bill admirably and I hoped Ruth would do the same in the fourth book. Everything looked hopeful that another great Peake character was about to develop then Titus wandered off again and she was out of the story. The same thing happened to all the characters, even the dog, and one soon realised that these were people that Peake had sketched with no hint of how they would develop, leaving Maeve Gilmore with the choice of trying to guess her husband's intentions (a tall order, to say the least) or simply move Titus on. Her choice of the latter course leaves the reader with a rather unsatisfying sequence of episodes but at least we have a glimpse of some new Peake characters.
I suspect that I am not alone in wishing that Titus had returned to Gormenghast (as the opening fragment suggested he might) to explore the tensions that his experiences in the wide world would undoubtedly generate with the surviving inhabitants.
Buy the book (it is cheap), read it and dream of what might have been!