Sheep's clothing Book

When Grace met Janice in Holloway Prison, she realized that Janice was a natural for her latest scheme. Posing as representatives of the Social Services Agency, they visit elderly people, promising increased pensions because of bureaucratic mistakes. While Grace chats with them, Janice makes them a nice cup of tea--thoughtfully adding some sleeping pills. When the victim falls asleep, the two women make off with all of his or her treasures. It seems like a good con--until old Miss Frimwell is found dead of an overdoes. Then detective Wally Simpson gets involved, becoming enraged as the pattern of their crimes emerges. But in a surprise ending, he discovers that he is more intimately involved with the scheme than he could ever have imagined...