Cloudsdale was at its peak of production, from rainbows to clouds and snowflakes and every shade of weather between. However, in the midst of their finest hour, the factory producing rainbows explodes, and with it, the other factories. Many pegasi were injured in the explosion, even the Wonderbolts won't fly for a long time after this. What will become of Cloudsdale, is far too terrifying to imagine.

The story is told in the point of view of Nurse Redheart, as she investigates the not-so-normal-for-an-explosion-injuries. Mysterious, fresh injuries on pegasus ponies continue to appear, even as they are hospitalized.