Ben Keegan is settling up his daughter Moira's wedding rehearsal at his estate. Peter Novelli, the groom, promises him he will care for his daughter. He asks for some money to set up an extravagant lifestyle for her. Disgusted, Ben walks away. Peter kicks a soccer ball into the woods and tells the workers to clean up. An unseen force throws the now-mangled ball back, but nobody notices.
Audrey and Chris are on a date and take a detour to the wedding to drop off the marriage licenses. Evi and Duke arrive to drop off some wine. Evi and Duke look at Chris and start fawning over him, much to his dismay.
Peter talks to his uncle Dom, who does not approve of him marrying a Keegan. As Audrey gives Peter the licenses, Ben walks up and declares the wedding cancelled, then angrily orders the Novellis to get off his property. As people start walking away, Audrey hears a scream from the bathroom. Inside is blood, debris, and a broken window. She goes outside and finds that her cellphone has no signal and the telephone line has been severed. There is a trail leading into the woods and she follows it.
Duke and Evi approach Beverly Keegan, a member of the Haven Historical Society, and try to ask her if she knows anything about the jewelry box.
Chris follows Audrey into the woods. They find Ben's glasses, covered with a fluid they can't identify. They walk back to the mansion, unaware that Ben's body is hanging from a tree, tangled in vines.
Vince and Dave visit Nathan at the station and say that they are headed for the wedding. They wonder why Nathan isn't coming, then figure that he's jealous of Audrey being with Chris and tease him. Nathan angrily brushes them off, and they leave. Nathan notices that they left behind an advertisement for their Tweet feed.
Beverly admires the box, but says there's nothing supernatural about it. It was made by Regis Glendower or someone from his shop. She offers to buy it.
Chris and Audrey return to the mansion and question Peter and Moira about why he and Ben were arguing. They are defensive, so Chris loses patience and uses his Trouble, making them fawn over him in an attempt to loosen their tongues. Audrey calls him out on this, but it works; Peter had wanted Ben to give him money and land. Peter runs off, so Chris follows him.
Audrey asks Dom if Peter has a Trouble, but Dom says that the Keegans are the ones who are Troubled. He pulls up his sleeves to show that his arms are heavily scarred, then claims that the Keegans did that. They hear a noise outside and investigate. Chris has found Ben's heavily mangled body outside, with marks similar to Dom's. Moira runs off screaming. Audrey wonders why this would have happened to Ben if his family is the one Troubled.
Vince and Dave call Nathan on the radio, using trucker jargon and asking for help because their van broke down on the way to the Keegan's mansion. Nathan agrees to help, as long as they quit spouting annoying trucker jargon.
Most of the staff have evacuated the mansion. Peter and Moira start arguing. The ground shakes and a staff member runs to her car. Vines extend and drag her into the woods, tearing her to pieces. More vines head for the others, and Audrey tells everyone to get into the barn. Dom and Beverly argue, accusing the other of causing this. The vines cover the barn, and Chris warns Audrey that they will eventually break through the walls.
Nathan drives up to Vince and Dave's van and tries to fix the engine. The vines appear and the three get into the van as the vines cover it.
Duke drinks some wine and asks Audrey if she has a plan. She tells him to try to find a way out and asks about Beverly. He says that Beverly did not approve of the wedding. Evi brings up that they were trying to sell the jewelry box, but Beverly needed Ben, because Ben controlled the Keegan's money.
Chris tries to find tools to fight the vines, but Audrey says they should concentrate on whose Trouble is causing this.
Duke and Evi go to the hayloft and try to force the door open. Evi notes that Duke has changed, he wasn't so selfless before. She says it's appealing and offers to run away together to Mexico when they get out of this. They open the door, but the vines are there.
Nathan looks over the van's emergency supplies and asks the brothers if they've heard of animated vines before. They have heard a few myths, then ask if Nathan is jealous of Audrey and Chris getting together. He insists that he isn't, then declares that there is a way out of the vines.
Audrey asks Beverly why the families were feuding. She says that back in high school, there was a fight between Dom and her brothers, and Dom killed her youngest brother. Dom angrily denies it. A vine bursts through the wall, and Duke tackles Audrey out of the way just in time. After a moment, the vine withdraws. Audrey realizes that the vines are animated by the hatred between the Keegan and Novelli families.
Chris and Audrey talk to Moira, who refuses to forgive Peter. The vines start breaking through the walls, and she says that she knew the story of how Beverly's little brother died. Moira then tells them that Ben took her to Packham's Point and showed her the tree that he claimed killed Beverly's brother. Audrey realizes what it means and confronts Beverly and Dom. She accuses Beverly of loving Dom and says that Ben lied to her because he was afraid that he'd lose control of the property and Beverly. Dom finally admits that they were preparing to elope. Beverly is surprised that he was there after all, and Dom explains that her brothers found out about it and attacked him. Then the vines attacked all of them because they were fighting, killing her brother despite Dom's efforts. Beverly apologizes and Audrey tells her she has a chance to make things right. They can use their love to push the plants back if they still have it, and Dom says it never went away.
Audrey gathers everyone at the door. Nathan suddenly arrives, burning through the vines with road flares. He says he only has one left, so get ready to run, but Audrey says that it won't be necessary. Dom and Beverly join hands and walk out as the vines part and recede. Peter and Moira join hands and follow. Duke and Evi join hands and follow. Chris and Audrey join hands, much to Nathan's dismay, and follow. Nathan sadly walks out last.
Later, Dave and Vince do some research and find that the Keegans and Novellis had a common ancestor, which was why both families had the Trouble. Dave tells Nathan not to wait too long to confess his feelings for Audrey. Nathan studies an article on the Colorado Kid murder, then picks up his cellphone.
On Duke's boat, he and Evi share a drink. Duke says that he's thought about her offer, but no, he's staying in Haven. Evi angrily accuses him of having feelings for Audrey, as she's seen him look at her and the desperation and concern on his face when he saved her from the vine. Duke denies this. She asks why he's staying and he says it's because of his father. His father made Duke promise on his death bed to come back if the Troubles ever return, but died before he could explain why. Duke insists that he can't go with her and walks away. Once he's gone, Evi calls someone and tells them that Duke's father never told him. The man at the other end says that they have to keep pushing Duke.
Chris comes to Audrey's apartment above The Grey Gull and offers flowers. He says that he's attracted to her not just because she is immune to his Trouble. She was able to bring two feuding families together and even got through to a cynical loner like him. She is the most amazing woman in the world. Audrey kisses him and they start having sex. Nathan tries to call her cellphone, but they don't notice.