'How to Get Away with Murder' season 3 spoilers: Bonnie, Frank hook up; unidentified victim is [SPOILER]

While fans were looking forward to seeing who will be crossed off the flash-forward victim list in the latest episode of "How to Get Away with Murder" ("HTGAWM") season 3, it was Bonnie (Liza Weil) and Frank's (Charlie Weber) hookup that really took viewers by surprise.

In "It's About Frank," Bonnie and Frank had a steamy reunion after the former travelled to Coalport to retrieve her father's ashes. After spending the night with Frank, Bonnie woke up the following morning to find that Frank had left her.

The pair's surprising hookup hints at a complicated dynamic between Bonnie, Frank, and Annalise (Viola Davis), which was further alluded to in the flashback in which Annalise and Sam (Tom Verica) helped Frank get out of prison.

Executive producer Pete Nowalk warned fans about an impending showdown between Bonnie and Annalise, telling Entertainment Weekly, "We're going to see how Annalise reacts to Bonnie seeing Frank in Coalport and how Bonnie is going to spin that."

"It's certainly a massive betrayal," he added.

Nowalk also hinted that Bonnie and Frank's rendezvous may be nothing new, saying that the episode hints that "they have a whole secret history between the two of them" and "that we're only starting to uncover it a little bit."

According to the "HTGAWM" boss, viewers may have been surprised to see the pair's tryst, but it didn't look like it was their first time.

Meanwhile, the much-awaited reveal on who will be eliminated from the victim list this week was tied with the return of a familiar face.

In the episode, it was shown that on the night Annalise's house burned, Oliver (Conrad Ricamora) was trying to get in touch with Connor (Jack Falahee). But Connor's phone was buried in the cushions of Michaela's (Aja Naomi King) couch and was answered by Trishelle (Brett Butler), Michaela's adoptive mom.

"[I]n the flash forward, the mother is there the whole time and she's there for a little surprise on Michaela," Nowalk told EW. "We'll just dig into more of what kind of environment Michaela grew up in and it's not what you would expect."

Apart from the revelation that Michaela is not the house fire victim Annalise recognized in the premiere episode flash-forward, the episode also showed a news report identifying that the dead person found in Annalise's house was male.

"How to Get Away with Murder" season 3 airs Thursdays at 10 p.m. EDT on ABC.