Titus Alone turns the whole world introduced in Gormenghast on its head: gone is the aloof gothic castle with its quasi-fantasy atmosphere and its days punctuated by rites and tradition, and in its place is a country of squallor and modernity, Bond-like contraptions and sentient machinery, sleek airplanes and smelly cars, menageries of animals and factories populated by identical drones. The only constant is Titus, wandering lost and alone, questioning his own sanity, discovering and rejecting friendship, love, sex, companionship, stirring in the melting pot of his own emotions in that hard road from youth to adulthood.
The novel is quite clearly published from an incomplete draft written before Peake's death (and for your own sake, get the 1970 revised version!) and it suffers from being incredibly and forcedly rushed in plot and execution. The size of the book itself is half of the previous ones, and it does feel as if half, or at least a good third, of the novel is missing: some scenes seem to imply a missing chapter before or after them, central characters are introduced but never properly developed, weeks and months go by in a few pages, and it seems to me that whatever happened to Muzzlehatch in the factory was supposed to be a story on its own and not just a flashback.
However, even from a draft you can still see the strength of Peake's writing and of his characters, fully delineated and unforgettable even after a few simple lines. Whatever awaited Titus outside of Gormenghast, this book was not supposed to be an ending but simply a new beginning.