Last spring, FX surprised comic book fans with a stunning depiction of a lesser-known X-Men story: Legion.

The series stars Dan Stevens (Downton Abbey) as David Haller, a man diagnosed as schizophrenic in his youth, only to discover after he's institutionalized that he might be the most powerful mutant the world has ever seen. The first season followed David on his journey to figure out if he was actually crazy or if his visions were his powers manifesting without him knowing.

As beautiful as Legion is to watch, it also takes a few viewings to totally understand what's happening. It's been a year since the intense events of the first season, so TV Guide is here to help and explain the major points of Season 1 so you feel ready to dive back in when the show returns for Season 2 in April. Here's what you need to know.

Aubrey Plaza, <em>Legion</em>Aubrey Plaza, Legion

1. David isn't schizophrenic, but he might still be a little crazy: David wasn't having visions of blob-like monsters in Season 1 because of a mental disorder. An ethereal demon known as Farruk, or The Shadow King, attached himself to David when he was a small child, acting almost like a tumor in David's brain that caused his hallucinations that made doctors think he was mentally ill. While David's visions weren't caused by a condition, living all those years with a demon in his head has had side effects that don't make David's judgement entirely clear.

2. The Shadow King is embodied by David's dead friend Lenny: Lenny (Aubrey Plaza) was David's closest friend in the institution, but she died shortly into the season after David's first major telepathic episode. However, she became the manifestation in David's head for The Shadow King. When you see Lenny on screen, it is actually Farruk trying to take over or find his next host. Sometimes The Shadow King also looks like a blob monster, but when he communicates with David or the others, it's through Lenny.

In 2017, Aubrey Plaza Redefined the Supervillain

3. David is in love: At the start of the series, David meets Syd Barrett (Rachel Keller) and falls in love. They have some serious barriers to overcome in their relationship though. Syd is also a mutant and she switches bodies with anyone she touches so they can't have any contact except in a private room David creates on the astral plane for them to escape to.

4. There is a war going on: Syd eventually helps David get the answers about his condition with the help of Melanie Bird (Jean Smart) at Melanie's Summerland headquarters. There, a group of mutants are working to take down Division 3, the government body hunting down dangerous mutants. Both sides want to have control of David thanks to his immense powers, but Division 3 is obviously more nefarious.

Clark (Hamish Linklater) is the face of Division 3 who managed to capture David in the early episodes, but David's powers manifested at the right time. He put a pen through Clark's cheek and started a fire that burned over 40 percent of Clark's body, which made Clark super excited to hunt down David at the end of the season. David was too powerful by the time Clark found him again and Division 3 realized they really didn't stand a chance against the most powerful telepath.

5. Melanie Bird isn't that innocent though: Division 3 is upfront about their desire to kill or at least subdue David, but Melanie has her own selfish reasons for wanting David on her side. Her husband, Oliver (Jemaine Clement), had been stuck on the astral plane for 20 years at the start of the series. David is the only mutant powerful enough to save him and bring him back to the human plane — which he does in the season's later episodes.

6. The reunion between Oliver and Melanie is short lived: The Summerland team managed to separate The Shadow King from David, but they couldn't kill the demon. Instead, the Shadow King attached himself to Oliver and the two escaped from Summerland together, heading off to parts unknown.

Legion: Here's Your First Look at Season 2

7. David has been kidnapped: Season 1 ended with David being abducted into a floating electronic orb after telling Syd that Farruk had escaped with Oliver and they were heading south. Season 2 will have to answer who took David, where did they take him and why?

8. Carry and Kerry Loudermilk are the same person: Melanie has a scientist helping her at Summerland named Carry Loudermilk (Bill Irwin). He has a female, kung-fu expert, Kerry (Amber Midthunder) other half who can separate from his body to help with the more physical battles. At some points Carry and Kerry look like two separate people, but they grow week if they are separated for too long and must merge back into Carry's body.

9. David is adopted: One of the big reveals of Season 1 is that David was adopted when he was a young boy. He's still in search of who his biological parents are. In the comic books, David is the son of X-Men chief Charles Xavier. Legion has shown flashbacks of David's adoption, including a wheel chair with the iconic X across the wheels, but it has not confirmed that David is Xavier's son.

Legion Season 2 premieres Tuesday, April 3 at 10/9c on FX.