Janet is visiting Ms. Frizzle's class to find out if they go on unusual field trips. She's not convinced when they get on the bus and head for the Planetarium. Although when the place is closed, she's surprised to see the bus sprout rockets and head off into space. The class visits the Sun along with the inner planets. While in the Asteroid Belt the bus gets hit by an asteroid and their map gets turned off. In the process of fixing the map Ms. Frizzle and Liz get lost in space. It's up to the class and Janet's knowledge to find Ms. Frizzle and Liz. Will the class be able to?