For some reason, every time Luna looks up at the Moon, she can't help but feel like she's forgetting something.

Then, one night, a mysterious stranger crashes onto her porch, claiming to have known her while she was banished.

What, exactly, has she forgotten?

In the same continuity as Homeward Bow, and, by extension, Ruby and Friends, though reading those are not strictly necessary to understanding this story. This is a reboot of the "Cosmic Masquerade" arc of the story.

Violence tag for a moment in Chapter 3 — blood-substitute is mentioned, but the violence does not occur on-screen.