THE MYSTERY OF THE MARTELLO TOWER

While Hazel Frump is almost 12 and her brother Ned is only nine-and-a-half, they’re closer than most siblings. Their eccentric, wealthy father has vanished, leaving them with their artist neighbor Frankie, who helps run the family art gallery. After Hazel finds some mysterious e-mail messages while snooping in her dad’s office, soon both kids are off to Canada to discover relatives and a family estate they never knew existed. Hazel’s a whiz at basketball and Ned’s specialty is chemistry; both skills come in handy as a major art fraud is uncovered, and worry over their father sends Frankie to Turkey to get him released from prison. Family secrets, underground passages, annoying bullies, hidden staircases, wild hailstorms and dastardly criminals pepper the plot, often distracting readers from solutions that are not, in the end, terribly obscure. Despite this flaw, the large cast of characters and the multiple puzzles combine to form a traditional mystery that is satisfyingly resolved. The somewhat drawn-out ending may indicate future adventures for the Frumps. (Fiction. 10-14)