While visiting Chicago, twins Ashley and Bryce catch up with old friends, visit the house where they grew up, see many reminders of their deceased father, and help search for their best friends' uncle, who disappeared days before his wedding.
While participating in a forensics contest, twins Ashley and Bryce investigate not only the disappearance of a college student but also behind-the-scenes dirty tricks during the public speaking competition.
When eighth grade begins, twins Ashley and Bryce get caught up in investigating why their principal left under mysterious circumstances, even as they struggle to get along with his replacement, who seems to be out to get them.
Bryce and Ashley Timberline volunteer to house-sit for some friends; however, as soon as they move in, strange things involving their neighbors begin to happen.
While Bryce investigates who has framed their friend Boo for robbery, twin sister Ashley tries to find the previous owner of a painting, which had a map and a large amount of cash hidden in back.
While Bryce and the twins' dying friend, Jeff, attempt a two-hundred-mile bike hike for cancer research, Ashley searches for Jeff's missing collection of autographed sports memorabilia.
After joining a tennis camp at a local country club, twins Ashley and Bryce Timberline are blamed for outbreaks of vandalism there, and must work not only to clear their names, but also to find the real culprit.
