"Gun, with Occasional Music" is confusing at times; I never did figure out the "babyhead" thing. For the sin of obtuseness, "Gun" is docked one star. But, there's an awful lot to like, too. The narrative voice drips noir's style and deftly negotiates Lethem's strange world. The plot has all the usual twists and turns one might expect of the detective novel. The characters are all interesting in one way or another. Metcalf, a PI, is a drug addict (Acceptol, with just a touch of Regrettol for that bittersweet edge); the requisite gunsel is a talking kangaroo. "Gun, with Occasional Music" somehow manages to use all the tools of the detective novel (cynicism, murder, twisty plot) and a certain kind of non-space-setting science fiction (dystopian future, bizarre uses of technology). The marriage is stronger, and stranger than any book has a right to be.