Twilight Sparkle is lost and broken, living a new life in a new town, she has forgotten who she truly is. Something happened to Twilight in Equestria that caused her sudden departure, and has half of Equestria scouring the planet for her.
"What did I do?" Is... not a question Twilight had thought of. She'd been happy, and content living her new life in Frostglade. However, she'd always felt like there were pieces to herself missing. Like, she'd lost something important.

When Sunset Shimmer and Trixie Lulamoon finally track her down after months of searching (and barely tolerating the other's presence), the reunion is not a happy one. Their presence has upset Twilight's new life by revealing the first step in unraveling the web of secrets bottled up in Twilight's psyche.

The three mares journey to a place of ancient magic, where they must piece together Twilight's shattered memories, solve the mystery, and then finally go home to where they truly belong. Of course, their journey will not be easy; dark shadows follow Twilight's every move, trying to stop her party from seeing the truth. If that weren't bad enough, it's not just Twilight Sparkle who is being tested by the challenges of the Nexus.