When Twilight returns Cerberus to Tartarus, the last thing she expects to find and happen is to meet the ruler of the realm herself.

Even less so when that pony, Penumbra, turns out to be an alicorn. As she spends more time with the mysterious mare, Twilight finds herself drawn to her.

Unable and unwilling to leave Penumbra alone, Twilight strikes a deal with her to allow her to leave Tartarus. A deal that will change both of their lives.