For the most part, Pretty Little Liars has erred on the side of caution this season, and it's all been a bit -- what's the word? -- boring. But tonight's episode ("Burn This") upped the ante by introducing one of A's favorite things: fire.

Things got explosive for the Liars at Hanna's (sad) wedding shower when A finally showed that "he" meant business. After all, the other As never set a Liar on fire. (MONA, WHAT'S GOOD?) That being said, "Burn This" was still a bit of a letdown. While it was great to see this new A take some dangerous new initiative, I wish "he" would commit a bit more. Commit to setting people on fire like you commit to your use of bargain bin emojis, A. Commit to causing mayhem like Alison and Elliot committed to one another under the twinkle lights in Aria's backyard. Just commit to something diabolical, A.

OK, now that I've gotten my desperate plea out of the way, let's talk about the most surprising revelations from Season 6, Episode 18:

Melissa was being threatened before Charlotte's murder.

Right before Charlotte's hearing, Melissa started getting threatening messages. The enigmatic harasser claimed to have a tape of Melissa confessing to burying Bethany Young the night of her murder. So Melissa complied. She agreed to drop money off at a disclosed location in exchange for the tape's destruction. She did her part, but did the person behind the threats do the same?

This new development would explain why Melissa made such a swift and silent exit. She didn't even say goodbye to Spencer before slipping out into the night and boarding a plane to London. Melissa is obviously running scared, which makes me highly doubt her involvement in Charlotte's murder. The Liars, however, are still pretty convinced Melissa is up to no good.

So, who is Melissa's mystery harasser? Is is Uber A, or the person who killed Charlotte? I'm erring on the side of Uber A on this one. Whoever blackmailed Melissa was on Team Charlotte -- and that's the same person who left threatening messages for the Liars at Ella and Byron's wedding. Amidst scrolling through the wedding photos, Aria discovers a hidden message: "Give me the killer... by election night." This person clearly wants to avenge Charlotte's death. As for her killer, that person is decidedly on the run.

Spencer and Toby once had a pregnancy scare in college.

In a gripping flashback scene, we learn that Spoby's relationship fell apart sometime in Spencer's sophomore year at Georgetown after a pregnancy scare. Toby wanted to raise the baby. He saw a life, and more importantly, a family, with Spencer, but that's not exactly the future Spencer saw for herself.

This scene was a total heartbreaker. It's not that I even hold a torch for Spencer and Toby, but their realization that their lives were headed in two different directions was truly hard to watch. It hurt because it was authentic. Whether it's a high school boyfriend, or a teenage best friend, people change. Just because you both start off headed in the same path doesn't mean it's going to stay like that, and Spencer and Toby's breakup beautifully exemplified this emotional coming-of-age moment.

As for the outcome of Spencer's pregnancy test, we're left to fill in some of the blanks. However, considering how empathetic she was towards Toby and especially Yvonne, it seems like that she had an abortion. When she called Yvonne, she told her that she could always call her if she needed someone to talk to, and her delivery was just so affecting. It was like she knew what Yvonne was going through.

It would also help explain why her and Toby seem so distant in the present. He wanted to keep the baby, and she decided to abort it. So it's no wonder he wanted to confront Caleb for leaking Yvonne's personal medical history to the press because he knows just how heartbreaking a decision like that can be. (For what it's worth, Toby gets a pass on hitting Caleb's beautiful face, but it's JUST THIS ONE TIME, Toby.)

Mona might be the one who called Charlotte from The Two Crows the night she was murdered.

Detective Tanner tells Aria that she matches a eye witness's description of the woman who called Charlotte from The Two Crows and that she has to join a police line-up at the station. Now, we know that Aria was with Ezra the night Charlotte was murdered, but Aria wasn't about to say that, especially after all the work it took to erase the security footage at The Radley. After the line-up, Aria eyes Sara Harvey leaving the police station, which most likely means that Sara Harvey was the one behind that glass.

Aria is rightfully annoyed at Tanner for taking Sara's word over her own, but at the same time, Tanner was only doing her best with the description she had, which was pretty sparse to begin with: "Attractive brunette making call; Jingling car keys; Keychain with pink dice." If anything, Aria should be flattered Detective Tanner thought of her before Emily and Spencer. Though, to be completely honest, Aria is totally the Liar I would peg to be carrying a keychain with pink dice.

By the episode's end, however, we discover that the keychain-wielding brunette is none other than Mona Vanderwaal, thanks to Emily's astute detective skills. Did Mona actually place the call to Charlotte from The Two Crows? We'll have to wait until next week to get the full story from Mona, but if there's one thing we know about our Original A, it's that nothing she says can be trusted.

Aria became A's latest victim.

Aria was having a really great day until Tanner knocked on her door. First, she found out that Ezra called his publisher Jillian and pitched Aria as the co-writer on his sophomore novel. She seemed open to the idea -- after all, she really loved the ~ feminine ~ voice Aria added to Ezra's narrative -- but the real question was, what about Aria? Was Aria ready to co-author a book with her first love? Hell yeah, she was! Aria has wanted to be a writer her whole life, and she's not about to say no to the opportunity now, even if it means working with her ex.

Those feels of joy and elation didn't last very long. While attending Hanna's awkward AF wedding shower, she suffers second degree burns after an attack from A goes awry. (Don't worry; she's fine.) It wasn't quite the explosive surprise we were hoping for, but at least we got to see some kind of action this season.