It is a gloomy age for the Equestrian Realm.

The annual Summer Sun Celebration on 21 June, 1444, was a dark day in history when the sun did not rise for a full day, the craters forming the "Hench in the Moon" disappearing without warning. The Equestrian Royal Guard, bolstered in recent years because of a global arms race, responded by implementing martial law. Many think the mythical Black Knight returned to bring a horrific apocalypse, only to be defeated.

Etheigh Holright, a Coltchester stallion who just received his pre-law degree, is scared like everybody else. Her Radiant Majesty's Office in Canterlot has been completely silent as to what happened. The Royal Guard is still enforcing martial law two weeks later. Most importantly for Etheigh, however, is that he has been without his coltfriend, Gorthy Eldwrit, who protects his safety.

That has changed. He has received clearance from the Ministry of the Interior to travel, as he had previously planned, from Coltchester to Ponyville, a small village in Cloudsdale Province that was unexpectedly chosen to host the year's Summer Sun Celebration. There, he can reunite with Gorthy, and pursue his legal aspirations by apprenticing under Tall Order, a renowned lawyer who has "retired without retiring" in the village.

When he comes, however, his sense of "safety" is shaken. Gorthy resides in a community of artists that he says are "safe" for Gorthy, despite some members making him feel "unsafe". Moreover, Gorthy tells him the new village librarian is "safe", and when Etheigh meets her, he finds out she's a friend from college, that Gorthy had insisted for the year Etheigh knew her to be "extraordinarily unsafe"...

Content warnings, ordered by prominence in the Long Night:

• Abusive relationships - This mostly includes economic, emotional and psychological abuse in romantic, parental, and other relationships, and such abuse of those with disabilities. This is a main theme of the Long Night that begins in the very first chapter.
• Some violence - There are certain important points at which serious acts of violence take place, and when characters are injured, but the Long Night does not go into massacres or explicit details.
• Some profanity - Profanity is occasionally used in the Long Night, though its use is mostly "when a character feels it appropriate", rather than "casual".
• Some sexuality. Despite early chapters taking place during heat season (a common premise for many a spicy story), sexuality is far from central to the Long Night, and is, at worst, vaguely alluded to or implied in short sections.