Competent handling of fairly high voltage ingredients -- for K.N. -- more or less improbable, but convincing as one reads. Old time imbroglio of two babies, half sisters (one legitimate, one bar sinister), exchanged at birth, and not meeting again until they come of age. There's a fortune at stake, but it takes a murder and some finagling to bring things out straight. Norris market -- no more -- no less.