If you know where to look, the scars of Twilight Sparkle's magical surge during her entrance exam are still visible in Canterlot. Surges from unicorns are always potentially dangerous, but Twilight has come across a disturbing idea.

Unicorns aren't the only ponies with magic. Earth ponies and pegasi also use the magical energies of Equestria to shape the world around them. Could they too have surges? Twilight is determined to find out.