Gr 3-6 All sorts of social problems can be found in this paperback mystery. Eleven-year old Jelly (short for Jalinda) and her nine-year-old brother, who has Down's Syndrome, try to discover who stole a $500 gold coin from a coin store in the mall that her widowed father manages. Then other small things are missing: a crossword puzzle book, donuts, pizza, shorts, sandals, etc. Meanwhile, Jelly deals with a woman who is interested in her father. She also meets Donny, a boy who is hiding in the mall, having escaped from his father who kidnapped him. Predictable and filled with cliches, the book's biggest problem is its frustrating ending. Jelly commends herself on finishing her first case but admits that she still doesn't know who stole several major items. Readers, who have been reminded about these missing items at intervals, get no satisfaction. Captioned, poorly executed pencil drawings appear in each chapter but often appear a page before the action they illustrate. Nancy A. Gifford, Schenectady County Public Lib . , N.Y.