How did Stranger Things season 1 end? How did Eleven disappear – and what happened to Will Byers? Did Jonathan end up with Nancy? What's the deal with Hopper?

If you need a reminder ahead of Stranger Things season 2, here's everything you need to know. And for more exclusive content, download the Radio Times special Stranger Things digital edition now.

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What happened in Stranger Things 1? The super short recap

Season one began in 1983. Researchers at Hawkins National Laboratory opened a rift to the Upside Down, a horrific alternate dimension, and things quickly spun out of control. A monster from the Upside Down reached through into our world and abducted local kid Will Byers, closely followed by teenager Barb.

Will's mum Joyce and the town's police chief Jim Hopper slowly started to realise what was going on and began a mission to rescue him from the Upside Down. Will's friends Mike, Dustin and Lucas launched their own rescue attempt.

At the same time, a girl with special psychokinetic abilities called Eleven escaped from the mysterious National Laboratory and teamed up with the boys to save their friend – but she herself was on the run from the shadowy government agents.

With the help of older kids Nancy, Steve and Jonathan, Will was rescued from the clutches of this otherworldly creature – but Eleven vanished.

The monster – dubbed the Demogorgon by the kids after a character in the roleplaying game Dungeons & Dragons – seemed to be defeated.

What happened to Will Byers and why did he cough up a slug?

The last we saw of Will, he was coughing up a slug-like creature in the sink and having horrific visions – but keeping this a secret from his family. It's clear that Will Byers has not come back from the Upside Down unscathed, because kids don't normally go around expelling slugs from their mouths. Ew.

Will's disappearance was at the centre of season one, after he vanished on his way back from a Dungeons & Dragons session with his friends. The terrified 12-year-old spent the rest of the series hiding in the Upside Down, making contact with his mother Joyce through electricity in her house: a crackly phone, a string of fairy lights.

Finally she and police chief Hopper busted into the Upside Down through the portal in the basement of the Laboratory, rescuing a very sickly Will from the Demogorgon's nest while it was away fighting the rest of the kids.

What is the Upside Down in Stranger Things?

Eleven may not speak very much, but she demonstrated the Upside Down to Will's friends in the language they could understand. Flipping their Dungeons & Dragons board over, she placed the figurine of a monster on the reverse side.

The Upside Down is an alternative, shadowy dimension – a sort of reflection or echo of our world. It's a world of decay and death existing alongside our world without us being able to see it. That's why the landscape mirrors the real Hawkins.

So why is this happening? Eleven discovered the Upside Down – and the creature named the Demogorgon – during an "experiment" she was forced to endure at the Laboratory. That moment seems to have teared open a gateway between its dimension and our own. After that, other portals appeared and the monster began to come through.

The Demogorgon himself (or possibly herself – let's not be sexist) is a tall humanoid figure without a face. The face kind of opens up like a really creepy flower head.

What happened to Eleven at the end of Stranger Things season one?

From the moment this close-shaved, terrified girl in a hospital gown turned up at a diner in Hawkins and started moving things around with her mind, Eleven ("El") was the enigma at the heart of Stranger Things season one. Will season two provide the answers?

In series one we began to piece together her backstory. "Eleven" was kidnapped at birth by scientist Dr Brenner, who was interested in using her psychokinetic powers for his own ends. Her biological mother is suggested to be Terry Ives, who underwent a CIA mind control experiment called Project MKUltra while unknowingly pregnant and is now in a catatonic state. Is the girl we know as Eleven actually Terry Ives' daughter Jane?

Having been raised as a lab rat by Brenner – who she called Papa – Eleven finally escaped. Mike and his friends Dustin and Lucas found her in the woods and took her in, hiding her in Mike's basement and feeding her Eggos.

Eleven helped the boys make contact with Will and showed he was still alive somewhere. But while Mike started to fall for her, Dustin and Lucas were more suspicious – leading to a major fight. Towards the end of the series the kids all reconciled and focused their efforts on finding their friend.

It all came to a head with a showdown at the school. When Brenner and his agents arrived at the middle school to capture Eleven, she managed to kill most of them using her powers – but was soon exhausted. Then the Demogorgon arrived.

Eleven made a final sacrifice, attacking the Demogorgon – but this caused her to vanish. Where is she now? In the final moments of season one we saw Hopper leaving her an offering of Eggos, so we know she's around somewhere.

What happened to the older Stranger Things kids?

While Will's friends are running around with Eleven, the older kids went on a journey of their own – and it involved mild stalking, teenage sex, and plenty of bear traps.

Mike's older sister Nancy made a plan to go to a secret party at her boyfriend Steve's house and dragged her dorky friend Barb along for the ride. But while Nancy was off having fun with cool kid Steve, Barb was taken by the Demogorgon and vanished.

The only witness to Barb's final moments was Jonathan Byers, Will's older brother, who just so happened to be hiding in the nearby forest with a camera taking photos. (He was looking for Will – honest.)

With Barb and Will both missing, Nancy and Jonathan began to team up, despite Steve's jealousy and general nastiness. They managed to collect a bunch of weapons and traps and boobytrapped Will's house, slashing their hands with a knife to lure the Demogorgon with their own blood.

Steve turned up, and it looked like he'd derailed the whole thing. However, realising there was something seriously amiss and that Nancy and Jonathan were both in danger, he heroically joined the fight against the Demogorgon.

After the showdown, Nancy and Steve got back together and both stayed friends with Jonathan.

What happened to Barb in Stranger Things?

She's definitely dead. While Will just about survived his trip to the Upside Down, Barb did not.

When Eleven went looking for both the missing kids in the Upside Down she found Will alive and hiding, but came across Barb's decaying corpse with a slug-like creature crawling out of her mouth.

Did police chief Jim Hopper betray the Stranger Things kids?

Hopper had a difficult choice to make as Stranger Things season one came to a head. In his attempt to rescue Will, he agreed to give up the location of Eleven, putting her in danger.

The gamble worked: he and Will's mum Joyce were allowed to enter the Upside Down, where they found Will barely clinging to life and rushed him to hospital. And while Brenner found Eleven, he wasn't able to capture her – because she vanished while fighting the Demogorgon. So that's kind of okay.

But what are the repercussions of this bargain? Towards the end of season one, we saw Hopper being picked up by the government agents, who whisked him away to an unknown location.

Hopper returns in season two – but can he be trusted?

Meet the cast of Stranger Things 2

Eleven – Millie Bobby Brown

Mike Wheeler – Finn Wolfhard

Will Byers – Noah Schnapp

Dustin Henderson – Gaten Matarazzo

Lucas Sinclair – Caleb McLaughlin

Chief Jim Hopper – David Harbour

Joyce Byers – Winona Ryder

Jonathan Byers – Charlie Heaton

Nancy Wheeler – Natalia Dyer

Steve Harrington – Joe Keery

New for Stranger Things 2...

Max – Sadie Sink

Bob Newby – Sean Astin

Billy – Dacre Montgomery

Roman – Linnea Berthelsen