Apex is a dizzying film with a tiny cast and a very creepy villain.

But while Baltasar Kormákur's survival thriller has plenty of dazzling action sequences and stunning cinematography, there's also a pretty dark origin story nestled in the cracks.

So what happens, and what does Jeremy Robbins' script suggest is the real motive of the film's serial killer? Let's unpack.

What's Apex about?

The film follows Sasha (Charlize Theron), a rock climber struggling to come to terms with an accident that killed her partner, Tommy (Eric Bana). Sasha pays a visit to a remote national park in Australia with the plan to go solo kayaking down a river, but her trip is upended by an encounter with Ben (Taron Egerton), a ranger hell-bent on hunting her to her death — seemingly, at first, just for his own twisted enjoyment.

Fortunately, Sasha is no stranger to surviving in extreme conditions. What follows is a cat-and-mouse chase across water, canyons, and cliff faces that's essentially a brutal hour-long fight for survival.

How does Sasha escape Ben?

Just as Ben has Sasha cornered in his killing cave (more on that later), she makes a bid for freedom: biting half his ear off and jumping from a ledge into the nearby river. Sasha's hands are bound, and she's attached to a rope Ben was planning to hoist her into the air with; this enables him to attach himself to her while the pair are dragged along by the current. When they finally wash up, Sasha breaks Ben's leg with a rock before he fights her off.

The problem? The only way back to safety is via a large cliff face, which they have to climb in tandem in order to escape. Ben threatens to pull Sasha off the wall if she tries to unclip her harness and leave him behind, but halfway up she manages to do exactly that when she's partly hidden by an overhanging ledge. Ben is thrown to his death while Sasha free solos the remainder of the wall to safety.

A radio news broadcast at the end reveals that authorities have uncovered 20 bodies from Ben's cave, and that he's responsible for numerous disappearances in the area that were previously attributed to the harsh landscape.

What's Ben's real motive?

Although the film doesn't tell us everything about Ben, we're given enough clues go on. The fact that he's a serial killer is indisputable, but while his initial motive appears to be a desire to hunt human prey, the scene in the cave reveals a darker secret: Ben is actually a cannibal who hoists his victims up like animals, eating parts of them and making other parts into a homemade jerky he sells at the nearby store.

"There are native tribes that say to capture the spirit of your prey, you have to consume its liver," Ben tells Sasha. "The trick is finding a spirit worth capturing, I suppose."

It's unclear what set Ben on this horrendous path, but his frequent mentions of his mother seem to be our best clue that he's been this way for a long time.

"She was special," Ben tells Sasha when she asks about the photo of him and his mom. "She was the first one. Do you understand? Now she's always with me. I'm gonna keep you with me too."

Ben, it seems, has become obsessed with the warped idea of hunting and consuming human prey as a means of growing more powerful.

Apex is now streaming on Netflix.