Isaiah, a tiny mouse, and his 96 siblings try to escape from the terrible place they’ve called home. As the youngest and smallest, Isaiah follows his brothers and sisters, believing they are heading toward someplace safer. Their escape route leads them through a tiny crack into the outside world, a place none of them have ever been before, and Isaiah is overwhelmed with fear. Their path is obstructed by a garbage bag, which causes the family to scatter. In an attempt to keep up, Isaiah takes a shortcut but gets trapped in the garbage. He frees himself after several frantic attempts but now finds himself alone with no sign of his family. He jumps into a nearby sewer drain, alone and scared.

Isaiah hears a siren and sees flashes of red light from an alarm. Despite his fear, an inner voice urges him to keep moving, and he relies on the agility and skills that his mother taught him to navigate the storm drain. He follows a shaft of light up into an alley filled with trash. He slips on a banana peel and skids through a narrow opening, after which he overhears two humans arguing about the mice’s escape.