Gloom hovers: Margo and Craig have to spend spring vacation at home while their parents go on a business trip. But when Mrs. Alice Tooey arrives in a red Camaro, it's obvious that she's no run-of-the-mill sitter. Briskly, she tells the incredulous children that her sister Velma (a witch) plans to destroy the town, but that she has stolen Velma's destroying substance (""T3"") and the children must help her dump it into a nearby lake. The disposal of the T3 doesn't go according to plan, of course, so the three have some unsettling adventures. With Mrs. Tooey's arrival, much activity and banter flourish; but, despite the fast pace, Dillon slips in intriguing details about the carefully portrayed main characters, plus various humorous happenings. A wacky, lighthearted tale of magic that should find plenty of readers.