Max and the book of chaos (EP)

On any stage except boss stage in Little Invaders, Nocturnal Experiments or Hell's Kitchen, shoot upwards on the cage with a classmate to rescue them. You need to rescue all 3 in a given stage to unlock this achievement. You can see an example of this being done on Little Invaders level 1 at 2:54 in the video.

Full Achievement Walkthrough video: