Jenna tells Elena that she’s discovered the identity of her birth mother.

Isobel Flemming, of Grove Hill, Virginia, gave her up for adoption when she was in high school. Jenna also gives Elena the address of Trudie Peterson, Isobel’s former best friend.

When Elena tracks Trudie down, she gives the sad seventeen-year-old a few answers about her birth mom - but she also clearly knows more than she’s letting on.

Trudie texts an unknown number to say “She’s here” after Elena shows up, then serves the girl tea made of vervain, a.k.a. vampire poison.

When Elena notices that something’s up, Trudie orders her to leave her house.

Trudie gets another surprise visitor: a man we’ve never seen before.

He thanks Trudie for the text, and murders her.

The specter of Isobel haunts the rest of the show’s characters as Jenna tells Alaric that Elena’s birth mother and his presumed-dead wife are the same person.

The history teacher then summons Stefan. He wants the vampire to drill his brother for more information about Damon’s relationship with Isobel.

But Damon’s being stubborn as always.

Eventually, thanks to a background check conducted by Sheriff Elizabeth, Damon learns the connection between Isobel and Alaric. At a benefit for Founder’s Day, he smugly implies to Alaric that he killed Isobel.

Elena, of course, is also at the benefit.

When she hears Damon’s apparent confession, she flees with Stefan in tow. The two run into a mysterious stranger outside of the benefit: the same man who offed Trudie.

“Stop looking,” he tells Elena when she steps outside. “She doesn’t want to know you.”

Luckily, Elena thinks to swipe his cell phone before she leaves the scene of the crime.

The next day, she takes it out and redials its most recent call.

A woman answers, asking, “Was there a problem? Did you find her?”

When Elena replies, “Isobel?” her mother hangs up.

Alaric, too, learns that Isobel isn’t exactly dead when he heads to Damon’s house after the auction, intending to stake him. Damon confesses that he “turned” the man’s wife - according to him, Isobel was begging to be transformed into a vampire.

When Alaric attacks Damon, the vampire nonchalantly stabs the man, then sits back so he can watch him bleed to death. After a commercial break, Damon exits the room, leaving his brother to stare at Alaric’s splayed body.

But all of a sudden, Alaric’s fingers twitch ... and he gets up! Does he have vampire blood in his system? No: he’s got a magic ring, thanks Isobel. The plot thickens.

As for Matt and Caroline, they’re busy dealing with Kelly, Matt’s mom. Kelly has finally come home after a long absence.

She isn’t shy about letting Caroline know she doesn’t like her, mainly because she hates Mrs. Lockwood.

But Kelly isn’t as strong as she initially appears: because her latest boyfriend has just dumped her, she has to depend on Matt for support. Her son assures her he isn’t going anywhere near the show’s conclusion.

Throughout the episode, the lone vampire who escaped from the tomb pops up a few times. He kills a hiker in the woods, then steals his 21st-century clothes.

He wanders around the town, marveling at modern times. At the end of the episode, he finds Pearl, one of the other vampires from the tomb. Pearl’s companion invites him in to her home.