Van de Wetering's books about Amsterdam's musical, Zen-ish cops--Adjutant Grijpstra and Sergeant de Gier--are always offbeat, but this one is more like off-the-wall. . . with lots of comedy and only the skimpiest mystery values. In the novel's first half, the duo desperately tries to pin a murder rap on meek bookseller Frits Fortune, whose wife has disappeared. (She soon turns up, alive, in disguise, on a bicycle. Don't ask why.) And then there's a real corpse: a Colombian businessman dead in a car trunk. But though the cops find lots of motives--drug-dealings, the businessman's womanizing--death was from natural causes (ulcers). It's up to psychically aware Grijpstra, then, to spot this as a ""mind-murder"" (a little Gaslight, a little ESP) and to link it to that first, missing-wife case. Some very funny sequences in the first half (inept cops, intellectual slapstick) but no conventional payoffs: more and more, van de Wetering seems to be writing mysteries for those who don't really like mysteries.