"Learning about paleontology and fossil hunting under renowned scientist Dr. Iris Prez while attending summer camp in Colorado, the Aldens investigate an outbreak of strange events that local superstition attributes to a bigfoot creature roaming the valley"--WorldCat.

While investigating the disappearance of Spotzie, Mr. Woods's beloved cat, the Alden children discover that they are being followed by a strange man, receive threatening phone calls, and uncover a number of mysterious suspects in the catnapping. Simultaneous.

When their grandfather arranges for them to spend two week at Sunny Oaks, the four Alden children enjoy settling into the routines of farm life but become suspicious about a mysterious horse locked in the stables.

"The Aldens visit Ireland and stay in a beautiful castle that's now a hotel. But at night they see a mysterious figure who walks with a lantern, and think it could be one of the legendary banshees"--

Can the Aldens figure out who's responsible for the bad press before the center gets shut down for good? Henry, Jessie, Violet, and Benny are excited to learn more about raptors when they volunteer at a rehab center for wild birds. But not long after they arrive, a series of strange events makes it seem like someone might be trying to sabotage the center. Who could the culprit be, and why would they want to cause trouble for injured birds?

At the same time that the Alden children's efforts to raise money for a new hospital wing are being sabotaged by nasty tricks, they find their attempts to befriend the new girl Beth frustrated by her strange behavior.

"Jessie and Benny are participating in the Great Greenfield Bake-Off, a local baking competition for kids. But ingredients get mixed up during the competition and then the power goes out. Is someone trying to put an end to the contest?" -- provided by the publisher.

"The Aldens try out a Halloween escape room. The puzzles are fun to solve. But when eerie events start scaring people away, the children find a much bigger case to crack"--WorldCat.

"Cousin Alice is running for mayor, and the Boxcar Children must find out which of her opponents is using sneaky tricks to win the race!"--Provided by publisher.

The Boxcar children uncover a mystery on a train trip from Boston to San Francisco.