While Nathan tries to return to Haven after Croatoan sends him away, Dwight defies the Guard to get the crystal back to Croatoan so that he can begin his experiments with Audrey at his side.
Croatoan sends Duke to attack the group when they come up with a way to restore the aether core. Meanwhile, Dwight and Nathan both face terrible choices when Croatoan offers them what they've always wanted.
Nathan and the Guard manage to capture Duke, and Nathan tries to get through to his friend. Meanwhile, Croatoan explains his plan to Audrey, and insists that he'll give the people of Haven everything that they've ever wanted... if Audrey cooperates with him.
The citizens of Haven gather at the police station to protect Audrey from Croatoan, but a traitor from within threatens their plans.
While Duke tries to convince Hallie to reopen the thinny, Nathan tries to escape from the Void where he and William are trapped. Meanwhile, Dave must consider making the ultimate sacrifice to stop Croatoan.
While Hallie opens a thinny so that Nathan can enter the Void, one of the new Troubled confronts Duke over what he did to her. Meanwhile, Vince and Dwight discover that Croatoan is killing the Troubled that might break his link to Dave.
Nathan and Vince use a Trouble to travel back in time to 1983 to try and find out how Croatoan was able to kill the Colorado Kid. However, Vince tries to stop the murder, while Nathan meets Lucy. Meanwhile, mysterious men in suits capture Duke and hold him captive.
Dave and Vince try to track down Croatoan, while Dwight, Audrey, and Nathan convince a Troubled woman to bring back Charlotte from the dead. In North Carolina, Duke has a vision of Haven's future.
The town's mysterious killer uses a Trouble to target Nathan, Dwight, Audrey, and Charlotte for death... and to stop them from recreating the Barn. Meanwhile, Duke and Seth search for the mysterious man who can drive the black tar from the bodies of sinners.
The Sandman puts Audrey in a coma and plans to force her to commit to him forever through a wedding ceremony in his dream world. In Massachusetts, Seth investigates reports of a girl phasing through a wall and finds Duke... and has no memory of Duke or Haven.
Nathan secretly tells Dwight and Audrey that Kira is trapped with William's hidden cache of aether, and they can't risk leading the townspeople to it. While Dwight and Charlotte go to free the girl, Nathan stands trial to stall for time until they can come back and prove that Kira is still alive. Meanwhile, Audrey recruits a Troubled man, Grayson, to help her deal with the darkness trouble.moreless
While the townspeople take refuge in the Haven school, a new Trouble stalks them from the darkness. Audrey learns how Dwight is keeping order, while Nathan takes a team on a desperate mission to restore power to the town. Meanwhile, Duke settles into a normal life but discovers that the Troubles have followed him.moreless
After Duke releases a new wave of Troubles, Nathan and Dwight try to help the victims--and their victims--while Audrey and Charlotte look for the man responsible for the fog wall. Meanwhile, Gloria and Vince get Dave drunk in hopes that it will trigger another Croatoan vision.
Duke makes a deal with Mara so he won't destroy Haven. However, Nathan needs Mara to cure Audrey. Meanwhile, Charlotte reveals the secret of Mara and Audrey's existence, and Dave and Vince try to find out the source of Dave's visions.
When someone abducts Mara, Duke goes looking for her and crosses paths with Nathan. Meanwhile, Vince and Audrey try to find the proof they need to convince Dwight that Charlotte is not who she claims to be.
As Duke threatens to explode from the Troubles that he contains, he turns to the only person who can help him: Mara. Meanwhile, audrey tries to deal with a new Trouble while her illness grows ever more debilitating.
While Dwight tries to convince Charlotte that she shouldn't call in the army, Nathan and Audrey race to find a cure for the illness striking the Troubled people in Haven. Meanwhile, Duke frees Mara.
Dwight befriends Charlotte Cross, the CDC doctor sent to Haven to investigate Dave's biopsy sample. But dancing bears and a mysterious infection threaten to expose the town's secrets to the world. Meanwhile, Mara convinces Duke that his friends are turning against him.
Audrey calls in help from the Darkside Seekers to find a way to communicate with Nathan. However, to learn what they need to bring him back, Duke has to agree to an unusual deal with Mara. Meanwhile, the hospital takes a sample of the infection on Dave's leg, and the analysis may endanger Haven's secrets.moreless
Nathan and Audrey are finally reunited but at a cost. However, their reunion is short-lived when Nathan is seemingly killed by a localized nuclear blast... only to find himself transformed into a ghost.
After the newest Troubled person switches their minds, Duke and Nathan try to use the circumstance to their advantage to fool Mara. she soon realizes what they're up to, forcing them to risk everything on one last, desperate plan. Meanwhile, Dave and Vince learn more about the circumstances of Dave's adoption in North Carolina.moreless
While Dave and Vince travel to North Carolina to explore the circumstances of Dave's adoption, a new Trouble strikes Haven. Meanwhile, Nathan takes a different approach to try and bring Audrey back.
Mara offers to cure the Troubles in return for Dwight's help recovering the aether that William hid. Meanwhile, Duke is plagued by a new Trouble, while Vince and Dave seek help to recover the memories they lost in the cave.
Nathan abducts Mara on his own so that he can bring Audrey back out... and keep the Guard from killing Mara. Meanwhile, Duke's friend suffers from a fatal Trouble and he needs Mara to cure her... and himself, as the Troubles within eat away at him.
While Duke's new Trouble runs rampant, Nathan sets out to capture Mara and turn her over the Guard in the hope that they can make her undo the Troubles. Meanwhile, Vince and Dwight disagree over the leadership of the Guard as Vince tries to deal with Dave's injuries.
Mara, occupying Audrey's body, goes on a rampage to find a way back to her own world. Meanwhile, a new Trouble with an old history strikes the residents of Haven, and Duke suspects that he might be the one responsible.