The Kind Worth Saving - Peter Swanson

TWO'S COMPANY, THREE'S MURDER When private detective and former cop Henry Kimball is hired to investigate a cheating husband, he senses all is not quite what it seems, and before he knows it he's gotten far too close to the other woman. As the case rapidly gets ever more dangerous, he's forced to turn to the only person he can trust, the sociopathic Lily Kintner, the woman who once stabbed him, but with whom he shares a peculiar bond.