Seven-year-olds Bradley, Brian, Nate, and Lucy make observations and gather clues that convince them that their older siblings, cousin, and animals have been captured by hungry space aliens.

Bradley, Brian, Nate, and Lucy follow clues on an Easter treasure hunt, while trying to figure out who set it up for them.

Bradley, Brian, Nate, and Lucy follow clues to find whoever left a rabbit in their first-grade classroom on Valentine's Day, because they are worried the rabbit will get sick and die of loneliness.

When three leprechaun statues disappear just before St. Patrick's Day, Bradley, Brian, Nate, Lucy, and other friends follow clues in order to prove that Lucky O'Leary is innocent of the crime.