Dissociative identity disorder - also known as multiple personality disorder - must be one of the most frightening psychological conditions. The sufferer's body becomes like a puppet, with a range of puppeteers and ventriloquists fighting over the strings and the voices. Whenever an alter ego wins control, the owner of the body becomes oblivious to whatever he or she is doing in the outside world. Weeks, even months, may pass while the victim is unconsciously carried around within their own animated corpse, only to wake up in a strange town, with strange people, having done something very strange, perhaps even criminal.
MPD is often the result of childhood abuse, as victims compartmentalise various elements of their personality. Thus, an extremely shy person will generate a violently aggressive persona. Some sufferers even have a caretaker soul, like a nominated driver, who will protect them from their worst excesses, or leave notes to explain what has happened.
It is a mark of Matt Ruff's narrative skill that his third novel (his first to be published in the UK) explains this complicated condition almost in passing. His protagonist, Andy Gage, has MPD; his soul was shattered by persistent sexual abuse from his stepfather "from an age before it was even obscene". With the help of a maverick therapist from Seattle he has learnt to accommodate his various personae in an imaginary house. Each of his souls has its own bedroom. Ruff even provides a plan, indicating the sleeping arrangements.
Andy has controlled his disorder to the extent that individual souls are granted time in the body's driving seat, while he keeps an eye on them from within the house. So Adam, the sex-mad adolescent, gets to riffle through Playboy; Jake, the eager kid, is allowed to drag the body into a toyshop; and Aunt Sam can steal a sly cigarette. These are the more innocent souls. Andy suspects that before he set his house in order, one of his personae - Gideon - murdered his stepfather. Together with Penny Driver, who also suffers from MPD, he sets out on one of the more memorable road trips in American literature.
Ruff weaves two storylines around each other: the outer world, where Andy races across America, is set against his inner landscape, where the various souls fight for possession. As real life becomes more complicated, so Andy's house becomes increasingly disorderly, and he starts to lose control of the body once again.
In the margins of Andy's psychological road trip is a dark satire on the American dream of self-invention. Andy discovers that, in an earlier incarnation, he left Michigan believing that he was done "with that whole chapter" of his life. "So I decided - I decided - to stay on the bus and keep going." Returning to the Midwest, he encounters his own traces in people's eyes and in the reception he is given by his home-town police. There may be multiple personalities in his head and multiple chapters in his life, but as far as the law is concerned, there is one body and one past.
Over the years, crime writing has moved out of well-lit bourgeois interiors, where bodies were habitually found in libraries, and into smaller rooms in darker houses. The comforting cycle of murder and redemption has been replaced by the fuzzy psychology of abuse and self-hatred. Set This House in Order, while gesturing towards this chilling form, is ultimately a good old-fashioned crime novel. It is as readable as the most golden of golden age mysteries but one where, like Oedipus, the protagonist is both criminal and detective, asking questions to which only he holds the answers.