Pretty Little Liars aired from 2010 to 2017, and quickly became an incredibly popular teen drama. Pretty Little Liars is centred around 4 main characters: Spencer, Aria, Emily, Alison and Hanna. The show begins with the strange disappearance of Alison DiLaurentis, who vanished one night the 5 girls were having a sleepover. The four devastated girls quickly become the victims of an intense series of blackmailing. Aria, Spencer, Emily and Hanna all begin receiving encrypted texts from "A" that feature secrets they've only shared within the group, which immediately leads them to the possibility it's Alison.
As Pretty Little Liars continues, everyone's respective lives hang in the balance as the girls are forced to take matters into their own hands. Aria, Spencer, Emily and Hanna don't feel safe going to the police, as the people implicated in the texts will face serious repercussions, and decide to investigate Alison's questionable disappearance and who A is, all by themselves.
5 First 'A' Arrest – Season 2
For the first time in season 2, the girls (and fans) get some form of resolution to who 'A' may be. On the night of the Masquerade Ball, audiences watch the 3 girls attend. All the while, Spencer and new victim of 'A,' Mona Vanderwaal, head up to the Lost Woods Motel after following a trail of clues left before her disappearance by Alison. The pair start searching the room – looking for clues to deduce who 'A' is.
After some shady and suspicious talk, Mona leaves the motel room to grab some more chewing gum whilst Spencer quickly deduces that Mona is 'A.' Spencer gets knocked out, and driven to the lookout point where Mona tells Spencer to join the 'A' team, or disappear. In a scuffle, Spencer accidentally knocks Mona off of the cliff. Towards the end of the scene, we hear a search-and-rescue-type team shout: "She's alive!"
4 Alison's Return – Season 4
Alison's return always felt as if it was on the cards, but many fans felt like it just couldn't be. After viewers watched Alison's body be discovered, her funeral, and the many scenes that showed her grave, it definitely felt like an unlikely event. That didn't stop the Pretty Little Liars writers, though.
In season 4, the girls head to the Rosewood Cemetery in an attempt to find Alison. They see a girl in a red coat from behind, and as she turns around and pulls down her hood, viewers were left shocked as there stands Alison DiLaurentis. Her first line upon her return: "did you miss me?"
3 So Many Murders – Seasons 3-7
Pretty Little Liars had a pretty high death toll by the end of the 7th season. While fans' four favourite characters were no saints,their lives weren't going to be the same after Alison's disappearance. Emily Fields killed Lyndon James in self defence in the third season by stabbing him in the stomach. Shana died from blood loss after Aria Montgomery hits her in the head in season 5. Hanna Marin accidentally hit Archer Dunhill with her car, killing him, in season 7. Lastly, both Hanna and Emily were perpetrators in the decapitation of Noel Kahn after fighting him off, before he tripped and fell on his axe in season 7.
2 Spencer's Secret British Twin – Season 7
Spencer's secret British twin was an incredibly dramatic and completely unbelievable storyline from Pretty Little Liars. A couple of hints were left in the earlier seasons – not enough necessarily for the tenuous jump – but they were there. Dr. Cochran explained that he had delivered "two" of Mary Drake's babies, and there was some serious tight-timing when Spencer was back at the Lost Woods Motel and then almost immediately after was at the airport with Wren.
Still, a mysterious evil twin sister didn't seem like a realistic component to Pretty Little Liars. Alex Drake, Spencer's evil twin-sister, turned out to be one of the main 'A's to fulfil her need for revenge for the murder of Charlotte. Alongside Alex were Mona (from seasons 1-3) and CeCe Drake under her birth name: Charles.
1 The Dollhouse – Season 5
The dollhouse is one of the creepier storylines in Pretty Little Liars. Hanna, Aria, Emily and Spencer wake up in orange prison-like jumpsuits in an underground dollhouse after being kidnapped. The effort 'A' went through to make the dollhouse must have taken years – the rooms are exact copies of the girls' bedrooms, and there's CCTV installed with a microphone allowing 'A' to instruct the girls what to do. There were rooms replicating Alison's bedroom, Alison's living room, the venue they had their prom in, a morgue, and a vault.
In the dollhouse, 'A' forces the girls to participate in sadistic games in a last effort to psychologically torture them (for example: asking Hanna who gets to have water that day, or playing siren at full volume over and over again). It's an intense series of episodes that take the theme of Pretty Little Liars from teen drama to full blown mystery thriller.