How to Get Away with Murder launched a pretty huge new mystery in its Season 4 finale, when a new law student named Gabriel Maddox (Rome Flynn) turned up at Middleton, prompting Frank (Charlie Weber) to make a mysterious phone call, saying "Her kid's here."

Whose kid he is and whoever was on the other end of the line are still completely up in the air, but the most popular theory is that he's Bonnie's (Liza Weil) baby that she thought she lost in childbirth in her teen years. Bonnie testified in court during a flashback in Season 4 that at the age of 15, while she was being raped by several men on a regular basis, she became pregnant, but lost the child during delivery.

Here's the thing though... she was only told the child had died, and thanks to the detailed files Denver (Benito Martinez) was apparently keeping on everyone on Annalise's (Viola Davis) team, we know that there's a very real possibility Bonnie's child is actually alive. DNA tests don't lie, after all! Even more compelling, the math actually shakes out in favor of this theory, since we know Bonnie is currently in her late 30s, making it possible to have a 22-year-old child (how old first year law students typically are) if she'd had him/her when she was 15.

How to Get Away with MurderFinale: Who Is Gabriel Maddox?

"Bonnie right now is more interested in making sure that the files that Denver had on everybody do not get exposed," Weil told TV Guide at the Television Critics Association summer press tour. "And there is stuff in that file about the possibility of Bonnie's child still being alive and other things about her past that we are going to get into this season."

Frank, on the other hand, is going to be investigating Gabriel Maddox from the get go, which is honestly probably not a great thing for Gabriel. The subjects of Frank's investigations almost never end up living happily ever after...

"Frank would appear to be the only person who knows who this is — also with whoever it is he's on the phone with," Charlie Weber says. "These are the only two people who know who he is, but neither know why he's there, and that is Frank's big concern right now... I will say Frank starts looking into him immediately, and so if Frank's any good at what he does, you'll find out little bits here and there."

How to Get Away with Murder premieres Thursday, Sept. 27 at 10/9c on ABC.

Liza Weil, <em>How to Get Away with Murder</em>Liza Weil, How to Get Away with Murder