Orcas Island mystery
Jan G. Johnson
While spending summer vacation with their grandparents on Orcas Island, Washington, fifteen-year-old Julian and his twin sister try to discover who is behind some unusual petty thefts.

by Michele Sobel Spirn (2000)
When they accompany their parents to London, fourteen-year-old Robin and her twelve-year-old sister, Joanna, find themselves involved in a series of mysteries as they tour the city with Robin's English pen pal. Includes a glossary and a brief guide to London.
Jan G. Johnson
While spending summer vacation with their grandparents on Orcas Island, Washington, fifteen-year-old Julian and his twin sister try to discover who is behind some unusual petty thefts.
James C. Dekker
As Megan digs deeper into her brother's murder, she finds that Danny was "known to police" and that nobody outside of her family cares about solving the crime.
Phyllis Reynolds Naylor
After several bombs go off around town, eleven-year-old Bernie Magruder becomes suspicious of various members of his family, causing confusion in Officer Feeney's investigation and around the hotel that his parents run.
Margi Preus
Francie plunges into her senior year of high school near Minnesota's Enchantment Lake, but when her long-lost brother, Theo, turns up, so does a dead body, and Francie is drawn into another mystery.