A friendly writer with a metal detector, the mysterious inhabitants of a tower house, and the discovery of a locket in the sand are ingredients for the Aldens' latest mystery.

"In 1989 someone is threatening to steal the crown jewels, so the Queen of England summons Mac B. to England to protect them--and when they are stolen from a locked dungeon cell, where Mac and Holcroft, one of the warders, are supposed to be guarding them, it is up to Mac to figure out how they were stolen, and whether the thief is the descendant of an Irish soldier-of-fortune who tried to steal them in 1671, or someone else entirely."--

The Aldens become involved in a community theater production of "The Wizard of Oz," which is systematically and mysteriously being sabotaged.

Amidst violent earthquakes, Jay and Lila try to determine whether the leader of a colony on a South Sea island is truly Adam MacKenzie, the presumed-dead missionary he claims to be.

"The Alden children discover clues that could help them figure out why a man vanished from a run-down yellow house on Surprise Island"--

Challenges readers to solve ten mysteries using the same clues as the ten-year-old detective Encyclopedia Brown, with answers given in a separate section.

When a mysterious letter written in code arrives at King's house for his human, Kayla, he follows the trail of the person who left it.

The town's ten-year-old walking encyclopedia again solves ten neighborhood mysteries. The final solutions to the cases are at the back of the book, giving readers a chance to compare their sleuthing skill to that of Encyclopedia Brown.

The Alden children are thrilled when a famous orchestra comes to their town to perform, and when an original Mozart score turns up missing, they solve the mystery of its disappearance.

Benny wants adventure and finds it as he and the other Alden children help uncover the plan of those who would prevent ballooning from coming to Lloyd's Landing.