A certain Mr. Dowson assigns the Kool and Lam detective agency to spy on his daughter. As a result, Donald Lam has to deal with two crimes at once: blackmail and murder ("On Thin Ice"). The novel "Widows Wear Mourning" also deals with blackmail; the honor of the woman is affected. In order to understand such a delicate matter, Lam needed all his resourcefulness and ingenuity. As, however, in the investigation of the drug smuggling case ("Not all the grass is green"). Justice was stymied, unable to find the main evidence - weapons. Donald Lam was once again ahead of the police.