In a small hiccup of insensitivity, Rarity finds out a secret Rainbow Dash hid from everypony she knew, and does so in a way she regrets.
To fix her mistake involves a trade, a fear for a fear.
Rainbow Dash decides to tackle one of these by taking her to a place where few ponies ever go.
To get to that place, they're going to go up.
Prereading and Editing done by HoofBitingActionOverload and Outcast9851
Cover art can be found here