Pop quiz. Please complete the following sentence: "There are days when I get up in the morning and stagger into the bathroom and begin running water and then I look up and I don't even recognize my own _." If you answered face, then your name is obviously not Jonathan Lethem. Instead of taking the easy out, the genre-busting novelist concludes this by-the-numbers string of words with toothbrush in the mirror. This brilliant sentence and a lot of other really excellent ones compose Lethem's engaging fifth novel, Motherless Brooklyn. Lionel Essrog, a detective suffering from Tourette's syndrome, spins the narrative as he tracks down the killer of his boss, Frank Minna. Minna enlisted Lionel and his friends when they were teenagers living at Saint Vincent's Home for Boys, ostensibly to perform odd jobs (we're talking very odd) and over the years trained them to become a team of investigators. The Minna men face their most daunting case when they find their mentor in a Dumpster bleeding from stab wounds delivered by an assailant whose identity he refuses to reveal--even while he's dying on the way to the hospital. Detectives? Brooklyn? Is this the same Lethem who danced the postapocalypso in Amnesia Moon? Incredibly, yes, and rarely has such a departure been pulled off with this much aplomb. As in the "toothbrush" passage above, Lethem sets himself up with the imposing task of making tired conventions new. Brooklyn accents? Fuggetabo