We’re told that, after a great war, society was split up into five different "factions" in order to sustainably maintain order.
First, we have Erudite, the smartypants faction. Then there's Candor, who value honesty above everything else.
Amity are real chill. Think of them as the hippies of the story. Dauntless are the fearless protectors – they run around a lot and climb buildings.
And finally we have Abnegation, the faction known for their altruism, which is why they run the government. Here is where we meet Tris. Though born into this faction, Tris never felt like she belonged.
Tris knows she doesn’t have to stay in Abnegation because when people turn 16, they are given the opportunity either to move to a different faction or stay put. They even have a fancy aptitude test to help them make their decision. Nifty, right?
But wait, what’s that? Tris’s test results are inconclusive? What could that possibly mean? Well, we’ll tell you: SHE’S A DIVERGENT!
[Pause for dramatic effect]
Later at the Choosing Ceremony, Tris is dealt a blow. She watches her "selfless" brother, Caleb, choose Erudite over Abnegation – a shocker for all involved.
Yep, we were stunned too.
During Dauntless initiation training, Tris meets Four, a high-ranking Dauntless instructor who comes to learn of her Divergent status. Rather than revealing her true identity (he ain’t no snitch), he endeavours to help her pass the Dauntless test undetected.
And then they fall in love. Which is all sorts of wonderful.
That would be Jeanine – she's in charge of Erudite. Turns out Erudite created a serum to turn the entire Dauntless faction into a mind-controlled army, built to destroy all of Abnegation, all in order for her to slide on into the leadership role and take charge.
Jeez, Jeanine – greedy much?
Luckily for Tris, the serum doesn’t work on her because she is Divergent (humblebrag). And guess what? It doesn’t work on Four either because – all together now – he is also Divergent! See, they’re made for each other.
The two of them manage to overthrow Erudite’s control of the Dauntless army but are now on the run, heading for Amity to seek refuge.
Hidden within Amity, our pair is trying their best to blend in – "trying" being the optimal word here. (Tris is a total badass now BTW. Look at those knife skills!)
Anyway, Amity-induced bliss doesn’t last too long because Erudite and the evil members of Dauntless come a-knockin'. Jeanine is on a rampage to find every Divergent possible, so they make a run for it.
They hop a train in the hopes of escaping the Dauntless soldiers...only to be confronted by a large group of angry-looking factionless.
Which is actually OK because it turns out Evelyn, leader of the factionless, is actually Four’s long-lost mother.
After a short and not-so-sweet reunion with Mama Four – where she informs them of her plan to unite the factionless and remaining Dauntless to take on Jeanine – Four and Tris make for Candor.
Meanwhile, over in Erudite, Jeanine is testing Divergents to see who can unlock a mysterious box, which can only be done by completing a series of faction simulations...which isn’t as easy as it sounds. In fact, it’s pretty much a guaranteed execution.
Then things really start to hit the fan. Erudite carries out a sneak attack on Candor, taking out everyone in their way with a serum that puts you to sleep...unless you're a Divergent.
It is here that they discover Tris’s divergence is the key to opening the box, yet before she is escorted away, Four and team swoop in to save the day. Phew.
Riddled with guilt (who wouldn’t be?) over the attack, Tris sneaks off in the night to give herself up, leaving an unaware Four back with his mother at factionless HQ.
(Not before she and Four get it onnnnnnnn. Mmhmmmm. That's right. Girl has to get some before going off to her imminent death – we totally understand that.)
Jeanine puts Tris through a series of hallucinative simulations, each one related to a different faction. She passes three of the five, but in the fourth simulation, Tris fails and seemingly dies.
Don't worry, it was all an elaborate hoax to help her escape. But Tris being Tris, shejust has to know what’s in that box.
Which she does: The box clicks open when Tris is finally able to forgive herself for the deaths of her parents, friends, and the general problems she’s been attributed to.
The mysterious box contains a message from a digital blue lady, who informs them that they were in fact part of an experiment to see if humanity could continue to thrive, and that the keys to the world’s survival were the Divergents.
Fortunately, before Jeanine could destroy the message and kill Tris & Co., Evelyn and the factionless army storm in to save the day and seize the box.
The message is broadcast all over the city, Tris is hailed a hero for unveiling the truth, and the whole city starts to hastily make its way toward the wall.