Full story
Three years after Westview, Agatha Harkness is still trapped in the Scarlet Witch's spell. She believes she is Agnes O'Connor, a detective in a crime show that only exists in her head. A mysterious teenager who refuses to give his name breaks the spell. Agatha comes back to herself, but without her powers. Soon Rio Vidal shows up, a green witch who is Agatha's old lover and rival, warning her that the Salem Seven are hunting her.
The kid, known only as Teen, wants to walk the Witches' Road, a legendary path that promises every witch her heart's desire. Opening the road takes a full coven, so Agatha gathers a group of washed-up witches: Lilia, a seer who experiences time out of order; Jen, a potions expert whose powers were bound; Alice, a protection witch haunted by a family curse; and Sharon, a Westview neighbor with no magic at all. Rio ends up joining too.
The road is a string of trials, each one set in a different period style. Sharon dies early on. Alice is killed when Agatha drains her power during one of the trials. Bit by bit, Teen reveals who he is: Billy Maximoff, son of Wanda and Vision, whose soul landed in William Kaplan's body after a car crash. He is looking for his twin brother, Tommy. Lilia sacrifices herself to save the group from the Salem Seven, and Jen gets her magic back after learning that Agatha was the one who bound it.
In the end, the truth comes out. Agatha never really walked the road: she used it as a trap to lure witches and steal their power. Billy is the one whose magic made the Road real. Rio is Death herself, and she wants to take Billy, whose second life breaks the balance. Agatha, who lost a son, Nicholas, centuries ago, chooses to save the boy and gives herself to Death with a kiss.
Agatha returns as a ghost, because she is afraid to face her son on the other side. Billy, now in control of his powers, accepts her company. The two seal the road's entrance, record the names of the fallen witches, and set out together to find Tommy, the thread left hanging.