'The Hunger Games' prequel ends on a grim note that may be confusing if you didn't read the book — here's what happened

• Warning: There are spoilers ahead for "The Hunger Games: The Ballad of Songbirds & Snakes."
• Dean Highbottom's fate may be confusing if you haven't read the prequel book of the same name.

"The Hunger Games: The Ballad of Songbirds and Snakes" ends with a grim character death that's easy to misinterpret if you're not familiar with author Suzanne Collins' prequel book of the same name.

In the closing minutes, the tormented creator of the titular games, Dean Casca Highbottom (Peter Dinklage), drinks from a small vial and slowly dies in a chair.

For nonreaders, it's easy to conclude that Highbottom — guilt-ridden from the continuation of a killing competition he had no intention of creating — committed suicide.

But that's not what happens.

Highbottom was murdered.

Highbottom is poisoned by Coriolanus Snow

At the end of the movie, Coriolanus Snow (Tom Blyth) pays Highbottom a visit under the guise of dropping off the belongings of Sejanus (Josh Andrés Rivera), the former classmate he had a hand in murdering.

But Snow wasn't stopping by to return a diploma.

Snow unceremoniously dumps Sejanus' belongings all over Highbottom's desk, subtly revealing a few vials of morphling, a highly-addictive drug Snow knows the dean abuses.

Though it's not explicitly clear in the movie, the book reveals that Snow secretly poisoned the vial Highbottom consumes.

In the book, Snow visits Highbottom, and they speak for a bit before the teen departs.

As Snow walks off, the book's final paragraph gives the jaw-dropping reveal of Snow's sinister motivations for visiting Highbottom, confirming he laced a vial with rat poison:

The book ends with Snow hoping that Highbottom realizes his student got the best of him in his final moments.

Why does Snow kill Highbottom?

If Highbottom's murder seems random, it's Snow's way of getting revenge on the dean.

Snow blames Highbottom for partnering him with a physically weak contestant to mentor in the games (who he falls in love with only for their story to end in disaster) and for sending him off to the districts to become a Peacekeeper.

Snow also resents Highbottom for his constant reminders of his family's poverty.

Highbottom sees Snow as an extension of his father, Crassus. Once the best of friends, Crassus stole Highbottom's idea for the Hunger Games in college without his permission and submitted it as a class project behind his back.

Highbottom, never wanting his horrid idea to go public, never forgave Crassus and, as a result, focused his eternal grudge, unfairly, on Snow's son.

Highbottom's impending death was subtly hinted at in the movie

In the movie's opening minutes, the camera focuses on a container of rat poison in Snow's bedroom. This is likely what he used to kill Highbottom.

In the book, Snow obtains the rat poisoning from an alley.

When boarding the train to District 12 late in the film, Sejanus tells Snow he has a few vials of morphling. After his death, Snow comes across the vials as he goes through Sejanus' belongings. At this moment, he's likely conjuring his plot against Highbottom.

Highbottom's death is supposed to be a nod to Snow's signature murder choice

In 2014's "The Hunger Games: Mockingjay — Part I," Finnick Odair (Sam Claflin) reveals that President Snow's (Donald Sutherland) weapon of choice is killing from the shadows by means of poison.

"The perfect weapon for a snake," Odair says in a rebellion video.

Snow utilizes poison to take out enemies and allies who pose a threat, as well as to punish those who disappoint him.

Notably, Snow forced former head gamemaker Seneca Crane to poison himself with berries in the first "Hunger Games" movie.

At the end of "The Ballad of Songbirds & Snakes," viewers are supposed to leave theaters with the horrifying realization that Highbottom is Snow's first poison victim.