Button Mash didn't used to be a pony. At least, not before he died.

After the collapse of a high-rise during the events of "The Mysterious Mare Do Well," Twilight decides that she needs to bring the Architecture industry into the new millennium.

A stallion stands with his nose inches from a speeding freight train. The road ahead is full of ponies who have something to say, but he can't hear a thing.

Sweetie Belle magically derails a science experiment, causing her to switch bodies with Rainbow Dash. They try to masquerade as each other, but the weather team needs help and Diamond Tiara, well, is Diamond Tiara.