Twilight makes a startling discovery in Ponyville one day. Pinkie Pie has stumbled across a box of weapons-grade plutonium! The mane six set out to find whomever left the box in Ponyville and keep their beloved home safe from harm.

Who is responsible for the plutonium? Will the meddling ponies (and their dragon, too) be able to stop them? And, most importantly, who left a half-eaten cupcake on the table? Read and find out!

Cover Picture Credit: United States Department of Defence. The image is in the public domain as a work of the US Federal Government.