TROUBLED WATERS (4) by Rachelle McCalla: FBI agent Heath Gerlach is working undercover as a Coast Guardsman. Partnered with guardsman Tracie Crandell, his job is to investigate the murder of her former partner and the shady practices that led to it. While Heath would like to tell Tracie who he really is, his investigation of her and her colleagues’ roles in a diamond-smuggling ring doesn’t allow it. Even though getting close to Tracie emotionally upsets him, Heath knows it’s the only way he’ll get answers. This sequel to McCalla’s Survival Instinct once again involves plenty of excitement with smuggling, diamonds and an unexpected villain.