The fifth installment in the All Souls series finds Diana Bishop, a witch and Yale history professor, at a crossroads. She and her vampire husband, Matthew de Clermont, are preparing to take their six-year-old twins, Becca and Pip, to England for the summer when three messages converge on the same May Friday. A flock of ravens descends on their New Haven home, draining color from the world; one delivers a bone ring and a cryptic message to Becca, who communicates with the bird as though she understands its language. Inside, Diana discovers a letter from the Congregation, the ruling council governing the three creature species of witches, vampires, and daemons, demanding that the twins be evaluated for higher magic, the advanced branch of witchcraft. A third message comes from Professor Gwyneth Proctor, a previously unknown great-aunt at Ravenswood in Ipswich, Massachusetts, who writes that it is time for Diana to come home and encloses a prophetic drawing from 1972 depicting Becca's hand in Diana's with a raven's shadow over them.
Refusing to spellbind her children as her own parents once did to her, Diana leaves Matthew with the twins and drives to Ipswich. She encounters a tight-knit local coven, including Meg Skelling, the membership committee chair, who shows immediate hostility. Diana's cousin Julie Eastey drives her to Ravenswood, a seventeenth-century saltbox on the salt marsh. There, Gwyneth reveals the family history Diana's father, Stephen Proctor, kept hidden. Stephen had a twin sister, Naomi, who died by suicide after failing a higher magic examination. His grief hardened into an ultimatum for Diana's mother, Rebecca Bishop: no higher magic, no contact with the Proctors, no passing these traditions to their children. Rebecca, a formidable adept, agreed because she loved Stephen and because she believed the Dark Path, the first and most demanding stage of higher magic initiation, was meant not for her but for her daughter.
Gwyneth reveals the Proctor family tree. The lineage descends from three key ancestors: John Proctor, a weaver (a rare witch who creates new spells); Dorcas Hoare, a practitioner of higher magic; and the enslaved witch Tituba, through her daughter Grace Mather. Twins with split magical gifts have appeared in every other generation, one becoming a weaver and the other an adept. Diana confesses that she, too, was a twin whose brother's embryo died in utero, making her a chimera who carries both abilities.
Granny Dorcas, a vivid Proctor ghost inhabiting the Old Place, the family's saltbox at Ravenswood, presents Diana with the black bird oracle, a deck of handmade divination cards created during the Salem witch trials. The cards indicate the goddess wants Diana to pursue all three levels of higher magic: the Dark Path; the Crossroads, the second initiation trial; and the Labyrinth, the final and most dangerous test. Gwyneth begins training Diana while Goody Wu, the coven's divination chair, teaches her oracle work.
Meg accuses Gwyneth of flouting coven rules by training an outsider and demands Diana prove herself at the Crossroads. Diana invites Matthew and the twins to Ipswich. At a Salem memorial ceremony, Diana's rage at an insult to an ancestor produces a lightning storm, and Meg blocks the family's departure until Julie intervenes. That night, Becca runs into the Ravens' Wood, the ancestral forest and source of Proctor power, drawn by a seventeenth-century ghost. Matthew passes through Becca's protective magical circle and plays with the ravens in a display of wild freedom that stuns Diana.
On the night of the Crossroads challenge, Diana enters the wood alone. Meg attacks, but Diana encounters shades that manifest her magical identity, including the tormented shade of Naomi, trapped with a broken tenth knot wound around her body. Diana reweaves the knot, freeing Naomi's spirit. The goddess declares Diana suited for the Dark Path and grants her a great gray owl named Cailleach as her guide.
The family settles into summer at Ravenswood. Chris Roberts, a human geneticist and godparent to the twins, arrives with Miriam Shephard, an ancient vampire and fellow godparent. Matthew collects DNA from Proctor relatives to map magical inheritance, and at a Midsummer Eve celebration, the Proctor ghosts emerge in force.
The fragile peace breaks when Janet Gowdie, Matthew's Bright Born great-granddaughter (part witch, part vampire), reports that Meg told the Congregation the word "BLOODCRAFT" appeared on Diana's skin during the challenge, a manifestation of the Book of Life, an ancient manuscript whose contents Diana absorbed years ago. Diana, Gwyneth, and Janet travel to the Bishop House in Madison, New York, to confront Diana's aunt Sarah Bishop and search for memory bottles, magical vessels that preserve a witch's experiences. The house yields a cupboard of bottles, including Diana's own childhood memories. Diana discovers her mother's book of shadows, a personal spellbook, and additional memory bottles disguised as perfume bottles. One reveals that Peter Knox, a Congregation witch, voyeuristically opened Rebecca's preserved memories at the memory palace on Isola della Stella, the island archive in Venice where the Congregation stores witches' bottled experiences.
Back at Ravenswood, Gwyneth opens a seventeenth-century memory bottle from Janet's mother, Griselda Gowdie, who visited the Salem gaol in 1692. The memory reveals imprisoned witches singing a bloodsong, a spontaneous magical hymn, and Diana's ancestor Bridget Bishop delivering a prophecy foretelling a discovery of witches, three families joined, two bright children, and the black bird oracle. A vampire identified as Matthew's nephew Gallowglass is present, and the cipher of Philippe de Clermont, Matthew's father, marks the escape route, confirming the three families have been entangled since Salem.
Matthew concludes the Congregation has practiced a form of eugenics, using the memory palace to rank and evaluate magical lineages. Diana resolves to reclaim the family bottles. Before leaving for Venice, she recklessly takes Matthew into the Proctor labyrinth to practice; when she carelessly mentions his dead son and brother, their ghosts appear, and Darkness nearly overwhelms Matthew until Diana's grandfather's ghost intervenes and rebukes her overconfidence. In Venice, Matthew's mother, Ysabeau de Clermont, creates a diversion during the Redentore festival while Diana and Janet infiltrate the memory palace through a forgotten cargo landing, bypassing the Labyrinth. Diana recovers bottles belonging to relatives across three generations but is discovered by Tinima Toussaint, a Congregation witch who destroys one of Rebecca's bottles before letting Diana leave.
The fallout is severe: Diana is reprimanded, and Janet is expelled from the Congregation. Diana and Matthew open one of Rebecca's personal bottles, experiencing her memory of telling Stephen she was pregnant, a moment of joy that helps heal the rift between them. On the twins' examination day, the Congregation sends Satu Järvinen, the Finnish witch who once tortured Diana, now reinstated and revealed as a weaver herself. Pip demonstrates powerful but imprecise elemental magic, while Becca summons a silver-eyed raven named Fiachra, signaling her deep connection to higher magic. Satu delivers a formal invitation for Diana to walk the Labyrinth on Isola della Stella the following summer and warns that Becca will eclipse her mother. As Satu departs, Diana traces the tenth knot in the air and seals an oath that nothing will stop her children from choosing their own paths.