See No Evil
When the local lighthouse crumbles into the ocean, the residents think it might just be a natural disaster but little do they know— Audrey/Mara and her motley crew caused the implosion. And speaking of Mara… sadly, the last time we saw Audrey she wasn't herself. After banishing her supernatural ex-boyfriend, William, to another dimension, she reverted back into Mara, her original personality.
Back in the present, everyone who was in the lighthouse when it collapsed has been scattered to random places around Haven.When Nathan finds Audrey, his joy is short lived. Turns out that Mara is only pretending to be Audrey so that she can find Jennifer and re-open the doorway that William disappeared into.
Once Nathan tells Duke about Mara's plan, Duke panics and tries desperately but unsuccessfully to find Jennifer on his own. Meanwhile Dwight learns that Mara has all of Audrey's memories, which makes it easy for her to move through the town undetected; and Vince takes Dave to the hospital for his bullet wounds to be treated.
As if all that wasn't bad enough, new Troubles have appeared in Haven and even though he can't prove it, Nathan knows that Mara is just attempting to slow the gang down so that they don't find her. Mara uses the extra time she has from the distraction the Trouble is causing, to find other possible doorways back into the dimension where William is trapped. She pretends to be Audrey but when challenged she can be deadly—killing without a moment's hesitation.
Later, when Vince finds the journal of Haven's founder, Sebastian Cabot, he tells Nathan and Duke that there are five potential "thin spots" around Haven that can be used to travel to William's dimension. Since the Lighthouse is gone and Mara couldn't access the doorway she found in the local coffee shop, Nathan decides that they should stake out the other three doors. Dwight is the one who finds Mara but she gets the drop on him before he can capture her. Not that it matters because the doorway Dwight was staking out is sealed shut too.
The one thing that Dwight does get from Mara is that she's not responsible for the current Trouble running rampant around town—a Trouble that hasn't been seen since 1929. Dwight tracks the Trouble to the Barrow family but soon comes to realize it's Duke who has reactivated it—the various Troubles in the Crocker lineage are finding a way to get out.
Nathan and Duke think that Jennifer has been running around and sealing all the "thinnies" before Mara can get to them but Mara scoffs at that notion. She also rejects the idea that any part of her still contains the residue of what was once Audrey Parker. She's proven wrong, however, when she tries to kill Nathan and can't.