Mr. Snatcher and his subordinates search for the boxtrolls by hitting boxes and seeing which ones respond to the impact. A couple of boxtrolls escape capture and flee to their underground civilization.

The Sad Man and the kids examine the properties rectangles have.

Alex, Marty, Gloria and Melmen each wake up in a box that has different dimensions. They realize that they are being transferred out of their zoo.

The Sad Man shows how rectangles can turn into triangles with diagonals.

The Hip Hop Harry crew sings and dances to a song that illustrates basic geometric shapes and examples of them in everyday objects.