In the town of Haven, Maine, a place plagued by supernatural afflictions known as "Troubles," the fourth season begins six months after Audrey Parker, a woman believed to be the key to stopping these phenomena, sacrifices herself into a mysterious barn. Her partner, Nathan Wuornos, a police detective immune to the Troubles, desperately seeks her return, believing his own death is necessary to end the curse. Meanwhile, Duke Crocker, a local smuggler whose family curse involves absorbing Troubles, emerges disoriented in Boston, where he meets Jennifer Mason, a woman who hears voices connected to the barn.

Audrey reappears as Lexie, working in a bar with no memory of her past or her true identity. William, a mysterious figure, manipulates Lexie, revealing that she is actually Mara, the original creator of the Troubles, and that he is her ancient lover. As Lexie slowly regains fragmented memories and her true, more ruthless Mara persona begins to surface, Duke grapples with his intensifying family curse, which now compels him to absorb Troubles, leading to a deadly confrontation where Duke is forced to kill his brother, Wade, who has succumbed to the power of the Troubles. Jennifer, with her unique connection to the barn, becomes crucial in understanding William's plans and Audrey's true nature.

The season culminates as Audrey fully embraces her Mara identity to confront William. She successfully banishes William through the lighthouse portal, but this victory comes at a cost: Duke's family curse is fully restored, and Audrey's memories of Mara solidify, leaving her irrevocably changed and the future of Haven uncertain.

Season 4 of Haven covers episodes 1-13. Here's everything that happened:

Season 4, Episode 1: Fallout - Six months after Audrey's sacrifice and disappearance into the barn, Duke emerges in Boston, disoriented and pursued. He encounters Jennifer Mason, who has been hearing voices related to the barn. Meanwhile, Audrey, now calling herself Lexie, works in a bar, unaware of her past. Nathan, believing Audrey's sacrifice requires him to die to end the Troubles, is targeted by the Guard. Dwight is now the Police Chief, and the Troubles are escalating.

Season 4, Episode 2: Survivors - Mysterious deaths plague Haven as residents appear to spontaneously combust. Duke confronts Vince about the Guard's intentions towards his brother, Wade, who decides to stay in town despite the danger. Jennifer narrowly escapes the fiery "Trouble," and Nathan works to stop the pyromaniac responsible. The episode concludes with Jennifer embracing her Trouble, and Lexie realizing she possesses skills she doesn't remember learning, hinting at her true identity.

Season 4, Episode 3: Bad Blood - A mysterious trouble causes victims to be found drained of all blood, leading Nathan and Dwight to investigate. Meanwhile, Duke absorbs the blood, gaining a dangerous "Trouble" himself, and William reveals to Lexie that the people around her are not real. The episode concludes with Duke absorbing the blood and gaining a dangerous new Trouble, and William making the illusory people disappear, leaving Lexie to confront her reality.

Season 4, Episode 4: Lost and Found - Nathan and Dwight investigate a series of child abductions linked to a man creating "Douens" out of desperation for a family. Meanwhile, Audrey, trapped in a collapsing barn between realities, is guided by William to find an escape. Jennifer, aided by Duke, begins to hear Audrey, and Lexie arrives in Haven, but it's not Audrey. The episode concludes with the realization that the connection needed for a sacrifice to save Haven is gone.

Season 4, Episode 5: The New Girl - Lexie, a woman who appears to be Audrey but with a different personality, joins Nathan to investigate a trouble that causes victims to become paralyzed. It is revealed that Lexie is a new incarnation of Audrey, and she is destined to kill Nathan. The episode concludes with Lexie seemingly accepting her fate, though her true feelings remain ambiguous.

Season 4, Episode 6: Countdown - People in Haven begin to turn to stone, forcing Nathan, Duke, and Lexie to race against time to find the Troubled individual responsible. Jordan McKee is killed by Wade Crocker, who then absorbs her blood to gain power. The episode concludes with Audrey stopping the petrification Trouble, but Wade Crocker succumbs to his addiction to the Troubles, leaving Jordan dead.

Season 4, Episode 7: Lay Me Down - A trouble causes injuries sustained in dreams to manifest in reality, leading to fatalities. Audrey and Nathan investigate the dream-inflicted deaths, while Duke confronts his brother Wade, who has become a serial killer driven by a thirst for "Troubled blood." Duke is forced to kill Wade to save Jennifer, and Jordan is murdered by Wade as he seeks to understand his curse.

Season 4, Episode 8: Crush - A deep-sea pressure Trouble causes Haven to implode, threatening to crush the entire town. Duke grapples with the recent death of his brother, Wade, and is instrumental in stopping the Trouble. Duke is forced to kill Wade to end the Trouble, and Nathan's own Trouble is temporarily cured. The episode concludes with Audrey and Nathan sharing a moment of peace, unaware of the larger forces at play.

Season 4, Episode 9: William - William, revealed to be the "boss" of the thugs and the cause of the hallucinations plaguing Nathan, Jennifer, and Dwight, attempts to manipulate Audrey. He admits to orchestrating the troubles to force Audrey to embrace her original self, Mara. William is ultimately repelled by Audrey, who refuses to love him, and he is left to continue his destructive path.

Season 4, Episode 10: The Trouble with Troubles - Audrey finds herself in an alternate Haven where "Troubles" do not exist. William reveals that Audrey herself is the source of all Troubles, and that she created them. Vince and Dave Teagues are murdered by William as he manipulates Audrey. Cliff dies after wishing the Troubles away, inadvertently causing the alternate Haven's existence. Audrey must decide whether to restore the original Haven or leave this peaceful version intact.

Season 4, Episode 11: Shot in the Dark - The arrival of the Darkside Seekers, paranormal investigators filming a reality show, complicates matters as they pursue a folklore monster known as a rougarou. Audrey and William are both shot but inexplicably healed, and William escapes. It's revealed that Jennifer has a mythical power that could be key to stopping William, and she is the intended victim of the rougarou due to her birthdate. The episode concludes with the Darkside Seekers deciding not to release their compromised footage, and Jennifer's true nature as a "child of ruin" is hinted at.

Season 4, Episode 12: When the Bough Breaks - A deadly curse causes people to drop dead after hearing a baby cry. William manipulates Audrey into activating a new Trouble to counteract it, leading to the mother's death when Audrey's attempt to absorb the curse fails. Audrey discovers a photo of herself from 1901 connected to the curse, and the episode concludes with William revealing Audrey created the Troubles, setting the stage for a dangerous path.

Season 4, Episode 13: The Lighthouse - Audrey embraces her Mara persona to confront William, leading to William being banished through the lighthouse portal. However, this comes at the cost of Duke regaining his family's curse, and Audrey's memories of Mara solidify, leaving her irrevocably changed. The episode concludes with the group realizing some doors are better left unopened.