The big truth bomb of Tuesday's Pretty Little Liars was that Mary Drake (Andrea Parker) had two children — meaning there's another Drake out there somewhere.

The Liars discovered that Mary had a second baby while investigating some old files of Jessica DiLaurentis. The paperwork didn't say whether the child was a girl or a boy or give any clues to where that child could have gone, which leaves room for a lot of possibilities.

Is Alison (Sasha Pieterse) Mary's second child? That could explain why Mary has taken to her so much, and wasn't willing to let Archer (Huw Collins) physically harm her. There were two files missing from Jessica's cabinet though — Aria's (Lucy Hale) and Noel Kahn's (Brant Daugherty).

While it's still unclear who Mary Drake's second child is — and whether Mary is aware that she had one — whoever it is will be at the top of the A.D. suspect list. A.D. warned the girls that if they find out who A.D. is before A.D. finds out who killed Charlotte (Vanessa Ray), A.D will kill them all.

Shay Mitchell, Lucy Hale and Troian Bellisario, <em>Pretty Little Liars</em>Shay Mitchell, Lucy Hale and Troian Bellisario, Pretty Little Liars

Some other important notes:

- We know why Jenna needs forgiveness: It turns out that Jenna (Tammin Sursok) still isn't over Toby (Keegan Allen). A flashback revealed that she tried to kiss him three years ago at a fireworks celebration, and that's why she came back to town seeking his forgiveness.

-Turns out Spencer isn't over Toby either: After having to let Caleb (Tyler Blackburn) go last week to figure out his feelings for Hanna (Ashley Benson), Spencer (Troian Bellisario) got another emotional gut punch from Toby. He revealed that he was never building the house for his fiancee Yvonne — it was all for Spencer. But after Yvonne was attacked in their air stream, Toby realized that she's the one he wants and said goodbye to Spencer. Spencer just can't catch a break.

- Aria and Jason DiLaurentis were a thing: Jason DiLaurentis (Drew Van Acker) is back and he's bringing a lot of secrets with him. The first is that something definitely happened between him and Aria during the five year time jump. Both of them were skimpy on details, but it was scandalous enough for neither of them to have told any members of their family or their friends. We're betting on a hookup, and if that's the case we'd like to see the tapes. Get on that, A.D.

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- Ezra's Habitat for Humanity girlfriend is still alive: Ezra (Ian Harding) is so over the drama of Rosewood. He just wants to elope with Aria to Italy, but just as she was about to say yes, the FBI shows up at his door to reveal that his ex-girlfriend might not be dead after all. Did you really think that an Ezria happy ending would be that easy?

- The Grunwald returns: The mysterious Mrs. Grunwald (Meg Foster) will return to Rosewood next week to help the girls with their stalker troubles. You know things have gotten sticky when the creepy former sorority housemother shows up.

Who do you think is the mystery Drake sibling?

Pretty Little Liars airs Tuesdays at 8/7c on Freeform.