When Kat travels from London to Palm Desert, Calif., to spend the summer with her grandmother, ""the ultimate movie star,"" Noni Waters, she finds herself participating in a wild charade in order to bring the two-time Oscar winner back for one last film. The premise here is as entertaining as it is hard to believe: a drunk Noni decides to borrow Kat's skateboard one night, and ends up spraining her ankle. Afraid to appear injured when she meets with the film's superstitious director, Noni convinces Kat to stand in as her double. Noni enlists her offbeat crew-a bossy makeup artist, elderly acting coach and two loyal staff members-to pull off the act in just a couple of days. Some scenes, such as Kat, dressed as her 62-year-old grandmother, performing skateboarding tricks for the director, are quite memorable. But readers may be troubled that Noni's serious drinking problem is never addressed, and that she sends her 15-year-old granddaughter out to be groped by a lecherous director without any warning; in fact, while the spoiled drama queen makes for an amusing character, she does not ever seem to mend her ways. In the end, a wacky plot and cast of characters may not be enough to win over the audience. Ages 12-up.