Iggy Peck and Rosie Revere have earned their places among the most beloved children's characters and have inspired countless kids and adults to follow their passions. Determined Ada Twist, with her boundless curiosity for science and love of the question "Why?," is destined to join these two favourites. Like her classmates Iggy and Rosie, Ada has always been hopelessly curious.

Why are there pointy things stuck to a rose? Why are there hairs growing inside your nose? She embarks on fact-finding missions and conducts scientific experiments, all in the name of discovery. When her house fills with a horrific, toe-curling smell, Ada knows it's up to her to find the source. But, this time, her experiments lead to trouble.