One of Us Knows

The novel follows Kenetria Nash, a woman with dissociative identity disorder (DID), a condition in which the psyche fragments into multiple distinct identities, or "alters" (also called headmates), in response to severe childhood trauma. Kenetria's alters, called the Bad Day System, share her body and inhabit a Gothic castle in their "inner world," a mental space where each has a distinct role. The system includes Della, the manager and current host (the alter controlling the body); Solomon, an assistant manager and Ken's romantic counterpart; Empress, a teenager; Mesmer, an emotional caretaker; Keke, a four-year-old child alter; Lurk, a quiet observer; and Rapunzel, a trauma holder (an alter carrying traumatic memories) locked in the tower. Ken, the system's former host, has been dormant for six years.

Ken wakes abruptly on a dock along the Hudson River, disoriented and wearing Della's clothes. Solomon becomes co-conscious (aware inside while Ken controls the body) and explains that six years have passed, a pandemic has killed millions, and Della has arranged a caretaker position on Kavanaugh Island. However, Della left almost no details and is not responding to anyone. Their apartment has been cleared, with only packed bags remaining. Ken reluctantly accepts this may be their only option.

A ferry captained by John, a local ferryman, takes Ken to the island. He explains that the Dutch called it Daybreak Island, where ship crews once hazed sailors by abandoning them overnight. Local legend held the island was cursed. John describes Simon Kavanaugh, a post-Civil War businessman who bought the island and built a castle based on paintings by his wife, Grace, who died of the Spanish flu. He claims Grace was rumored to have been passing as white.

As the castle comes into view, Ken and Solomon are stunned: It is an exact replica of the castle in their inner world. An unknown alter screams "We promised!" in Ken's mind, urging her to flee with overwhelming panic. Ken suppresses the episode and decides not to tell Solomon.

On the island, Ken meets Celeste, the Black groundskeeper, who insists Ken should leave. Celeste corrects John's narrative: Grace was white, from a plantation-owning family, and the passing rumors were slander. Kavanaugh was a vice crusader who harassed and jailed women, Black people, and the poor while enriching himself.

That night, Ken explores the castle and glimpses a white dress in a dark hallway before a violent gust of wind drives her back. She discovers a watercolor of the island by Grace, with a pencil sketch of a woman labeled "Lottie" on the reverse. In the inner world, Solomon discovers Della's window shattered from outside, the void beyond the castle filling with a painted landscape of Kavanaugh Island, and headmates going missing.

The next day, Landon Kavanaugh Pearson, Ken's ex-boyfriend and an associate member of the island's conservation trust, appears and insists Ken was never selected for the position. He grabs her arm aggressively, but Celeste intervenes. Solomon realizes Della may have lied about the job and concealed Landon's family connection to the island. A journal found in the castle reveals Grace's private writings: She was forced into marriage after Simon caught her with her lover, Lottie. Later entries reveal Simon locked Grace in the tower and used the island for organized hunts targeting women. In the tower, Ken has a vision of a faceless woman in a white gown screaming "You promised!" Scratch marks on the tower door suggest someone was once locked inside.

Winslow Pearson, Landon's father and head of the trust, arrives with his much younger wife Lily, two board members named Gary and Klaus, and two hired women. A nor'easter traps the group on the island. Pearson confirms Ken was hired, calling her presence "necessary," and delivers a speech casting Kavanaugh's vice crusade in goblin folklore, with goblins paralleling immigrants, women, and minorities.

Ken wakes in the tower covered in blood. Pearson lies dead in the hallway, his skull caved in by a candlestick bearing Ken's fingerprints. The CB radio is smashed. Ken realizes the scene has been staged to frame her. Landon accuses Ken and claims Della recently threatened to "make his father pay." Solomon reveals that headmates have been vanishing in the inner world and admits he suspected Ken. Devastated, Ken tells him to stop speaking to her.

Landon announces the "goblin hunt," a tradition in which men chase women through the island at night. Gary forces compliance with a pistol. Ken and Celeste flee into the storm, where they witness Klaus strangling Diana, one of the hired women. Ken intervenes, and Diana stabs Klaus with his own ceremonial knife before fleeing into the woods. Ken and Celeste re-enter the castle, overpower Lily, and confirm via walkie-talkie that Landon and Lily conspired to murder Pearson and frame Ken.

In the inner world, Solomon pleads with Rapunzel to share the system's origin memories. Rapunzel is revealed as a nonhuman headmate embodied in a suit of armor holding a Claymore sword. Rapunzel places the skull-faced helm over Solomon's head, plunging him into recovered memories: As a three-year-old in foster care, Keke was brought to Kavanaugh Island by her foster mother for a "party" that was actually a goblin hunt. Young Landon attacked her with a baseball bat, but Keke found refuge in the tower, where the ghost of Lottie, Grace's lover, kept her safe through the night. Solomon realizes Ken is not a persecutor (an alter seen as harmful) but a protector (an alter formed to defend the system) who returned when they were brought back to where the system was born.

The ghost Ken has been seeing is Lottie, an introject (a headmate modeled on a real person) who has existed within the system since that traumatic night. Lottie has been the system's hidden gatekeeper, managing memory access and switching between headmates. She secretly fronted (took control of the body) when Della was overwhelmed during the pandemic and accepted the job invitation to confront the system's origin trauma. Ken enters the inner world by painting a pathway across the water. She confronts Lottie, discovering that Keke has a subsystem (a DID system within a headmate, with its own alters) with Lottie as one of her alters. Ken makes a pinkie promise never to abandon Keke again, and the system begins to reunite.

In the outer world, Ken regains consciousness in a flooded pit where John has thrown her to drown after slitting Landon's throat. The system works together: Lurk keeps the body afloat, Mesmer controls breathing, and Solomon helps them climb out. They re-enter the castle and confront John, who has tied up Celeste and Lily. Mesmer's tai chi training manifests as precise strikes. Not-Rapunzel, Rapunzel's new protector form, helps Solomon wield the Claymore sword, and Ken delivers the killing blow at dawn.

One week later, Ken and Celeste shelter at Celeste's cabin after being cleared by police. Celeste also has DID; Lottie's romantic ties with members of Celeste's system originally connected the two groups. The system's roster lists all headmates as active, with Ken reclassified from persecutor to protector. In the inner world, Solomon has furnished Ken's turret room, and they share a kiss. A blank canvas in the cabin invites Ken to reclaim her artistic identity as a gift shared among the system.