Disguising a Firework

Caitlyn is a good friend to her slightly odd companion, Sarah. They sometimes argue, but Caitlyn usually wins because she's been on Earth longer. But when Sarah decides that she wants to become famous, she'll do nearly anything to do it. Anything includes revealing her status as an alien, and so they find themselves hiding more than once.
As Sarah is ignorant of their danger, it's up to Caitlyn to save both their lives on this strange planet.