Using imagination, reasoning, and boundless enthusiasm, inventor Addison loves to solve mysteries with her friends.
When Addison and Alex taste the new pizza that Mr. DiGiovanni has created especially for Tess’s birthday, they find out it doesn’t taste good at all and so they set out to investigate what the problem is. Has Mr. DiGiovanni lost his sense of taste?
Ms. Bell’s wedding is in peril when a ghost scares away the customers from the beauty salon where everyone is getting ready for the ceremony. But Addison thinks the rumbling and drafts might have natural causes.
Addison goes undercover when it appears that someone is stealing raspberries from the community garden – raspberries that she and Tess need to get their next Ayrton Rangers badges.
Addison has to figure out why Alex can’t kick a soccer ball nearly as well as he used to, in order to correct his game in time for him to pass the team tryouts. Alex thinks he’s jinxed, but Donnie has a vested interest in making sure Alex doesn’t make the team.
Addison, Kevin and Tess are trying to make a rap music video for Ayrton Park’s Summer Fest Movie Night, but a persistent very LOUD buzzing from above keeps ruining everything! Addison sets out to solve the mystery of what’s making all the noise.
When Tess and Alex suddenly start getting electric shocks for no apparent reason, Addison has to solve the mystery or it will be lights out on their act for the school talent competition.
During a summer heat wave, something or someone – perhaps a cryptid Camenel – keeps draining the water from the wading pool.
When Ms. Bell’s prized apple-hologram marble – a gift from her own favourite teacher at teachers’ college – goes missing, Addison is on the case to find out how it disappeared from inside the locked classroom.
When Donnie, the obnoxious class semi-bully seems to have developed psychic powers, Addison has to figure out how he’s doing it and stop him from intimidating the other kids.
When Gyro the robot appears to be unhappy, Addison has to figure out what’s wrong with her little friend.
When the honey in the community garden’s beehive turns bright indigo, Addison is on the case to find out what’s giving the bees the blues.
When it appears that half of the cookies Tess and Addison baked for a charity event go missing, the girls are mystified. Could somebody have eaten an entire table of cookies? With a trail of crumbs as a clue, they chase the cookie crunching culprit.
The annual winter carnival seems to be in trouble when Addison and Alex’s yeti sculpture appears to have been vandalized… perhaps by an actual angry yeti!
When strange symbols begin turning up in Ayrton Park, Alex begins thinking that an alien invasion is imminent. Addison is sceptical but there are disturbing signs that the symbols that keep turning up spray painted on the sidewalks and roads just might be invaders communicating with each other.
Addison has to find out what’s wrong with Mrs. Rorschach’s cat, Mr. Tiggles, when he becomes afraid of his own cat toys, especially the new fridge magnet mouse.
When a cryptic message turns up in a bottle in the Ayrton Park wading pool, Alex suspects it's from Ancient Egyptians or someone shipwrecked on a desert island – but Addison thinks there must be another explanation.
The Junior Rangers weenie and marshmallow roast fundraiser is in danger of being shut down because of a ban on open flames. Addison meanwhile is investigating a mysterious case of Tess’s melting chocolate statue of herself (causes by mirrors) and is inspired to build a solar cooker to save the day on the weenie roast.
When a geocached item seems to have disappeared along with the soil it was buried in, Addison is intent on finding out what happened to it.
When the drains at Pizzamat and Hang 20 start backing up, Alex knows exactly what’s caused it – a sewer-gator or maybe a blob monster from outer space. Addison has other ideas however, and is determined to solve the mystery.
When Addison’s mom, Detective Patel, comes to the school to talk about her work as a detective, she intrigues Addison and the other kids by revealing that there’s an old neighbourhood rumour that a stolen art treasure, the Magnifical Mau-Mau, is hidden in their school.
