On a late June morning, Adam Parson takes his fourteen-year-old son, Eugene Parkson, to River Falls Park and does not come home. At 11:38 a.m., dashcam video shows Eugene running alone near the family’s neighborhood, which causes a driver to swerve and crash. College-age daughter Mia Parkson, distracted by a breakup call, misreads footsteps on their property as Adam’s return and delays sounding an alarm. When her mother, Dr. Hannah Park, and twin brother, John Parkson, arrive midafternoon, they realize Adam is missing and launch a search while trying to keep Eugene regulated. As police knock at their door about the car incident, Mia hurriedly washes Eugene’s muddy, possibly blood‑stained clothes and scrubs his nails, fearing misinterpretation.

Detective Morgan Janus takes the case, balancing reassurance with a hard insistence on “all possibilities,” including suicide. Search teams scour the park with dogs, drones, and helicopters. At home, Mia finds a backup drive and notes pointing to Adam’s mysterious “HQ” files and a conspicuous life‑insurance policy. The next morning opens with Eugene’s piercing scream—a rare, grief‑like sound Mia last heard the day their grandmother Harmonee died—intensifying dread. A brief flurry of texts from Adam’s phone (“Who is this?” then “Mia?”) seems like a lifeline until the signal dies; later Mia learns Janus had recovered Adam’s phone and replied from it.

At the park lot, Mia and John find no trace of Adam. Janus soon reports Adam’s backpack was pulled from the river, his phone protected but the contents soaked, including a green spiral notebook labeled with H and Q. As the odds tilt toward loss, the family studies scanned pages: Adam is defining a “Happiness Quotient” (micro versus macro well‑being), debating Angelman gene therapy, and contrasting his children’s outlooks. Financial records add new shadows: a secret account with $20,000 and intense recent contact with a woman named Anjeli Rapari. A retrieved voicemail from Anjeli urges Adam to stop hiding a plan and to tell Hannah. Then a $1,000 ATM withdrawal fifty miles south suggests either flight or theft of Adam’s wallet. Theories multiply—runaway, affair, suicide, accident—none satisfying.

When a CPS/AAC consultant arrives to interview Eugene, old wounds rip open. Years earlier, the family tried physically supported writing (PSW) with a trainee, TFT. Apparent breakthroughs collapsed when Adam staged a blind test that exposed facilitator influence, devastating Hannah and reshaping family roles. Now, a plastic stencil letterboard—like one found in Adam’s backpack—reappears. Eugene fixates on it; a chaotic scuffle follows when he thrusts a pen through the D, and Janus, injured, handcuffs him and moves for custody. At a juvenile intake hearing, Janus plays a neighbor’s video showing Eugene clawing at Adam during a park meltdown; Officer Higashida orders secure placement. A Covid quarantine blocks admission, and Eugene is placed on house arrest instead.

Defense attorney Shannon Haug consolidates the case and lays out scenarios to keep Eugene home: accidental drowning, suicide tied to possible cancer screening, running off with a woman, or a staged experiment—anything that is not a crime by Eugene. The family races to find corroboration. Leads swerve: a false ATM match in Charlottesville; then Adam’s mangled wallet is found upstream under dubious circumstances. A contact‑tracing voicemail identifies Eugene as a June 20 close contact, likely linked to a Saturday session with Anjeli.

Driving to providers blocked by Covid closures, Eugene bolts from the car, retrieves a hidden key, and enters a suburban walk‑out basement he clearly knows. It is Anjeli’s house. Inside, binders and videos reveal that since October, Adam has been taking Eugene to Anjeli for a staged motor‑to‑text method (“poke, point, type”). In a recent session, Eugene slowly spells answers and even jokes while Adam looks on, overjoyed; the warmth between Adam and Anjeli reads intimate, and the secrecy feels like betrayal. The family confronts fluency bias—how society conflates speech with intellect—and recognizes how easily they’ve underestimated Eugene.

Pressed by the legal clock, they prepare to try the letterboard at home, but new swerves complicate everything. A birder’s long video captures the river at 11:17 a.m. on June 23; over the roar, Adam’s voice yells, “Eugene, no.” Mia and the family decide to withhold the recording to avoid prejudicing officials. Shannon argues they need a coherent narrative that fits the evidence and clears Eugene. That night, Mia and John logic‑chain a plausible scenario at a high waterfall overlook: teens rifled Adam’s pack, tossed it toward the cliff, Eugene reached, Adam grabbed him, shouted, and saved him—but lost his own footing and fell. The story both comforts and unnerves Mia; she fears naming a story can make it real, whether or not it is true.

At dawn, Janus arranges a remote letterboard session with Anjeli, who is just out of Covid isolation. Before starting, Anjeli reveals that on Saturday Eugene vented furious words about Adam and wished him gone; her partner, Zoe, inadvertently showed that note to police, creating motive in the investigators’ eyes. With a stand‑mounted stencil board Adam built for independence, Eugene spells. He recounts that on Monday night he and Adam reconciled. Adam apologized for delaying disclosure until Eugene could prove independence (ideally via eye‑tracking) and promised they would tell the family on Tuesday. At the park Tuesday, a woman pepper‑sprayed Eugene during a confrontation; after Adam helped him recover, Eugene spelled forgiveness on a rock‑propped board, and Adam photographed two pages to show Anjeli. They ate lunch, talked about HQ, and moved to the quieter green trail toward a high waterfall overlook. There, three boys mocked them, stole Adam’s wallet, and hurled the backpack toward the drop. Eugene tried to catch it, slipped on uneven ground, and as Adam grabbed his arm, Eugene screamed. He fell back, briefly lost awareness, and when he opened his eyes, Adam’s hand was gone.

Shannon submits the recording and transcript to police and seeks dismissal. Janus pushes back, arguing the family saw the birder clip first and that Eugene’s account fits “too perfectly.” She questions the missing photographed pages and Eugene’s sudden communication. Then John checks pockets and produces Eugene’s dirtied shorts from the day; inside are the two pages in Adam’s block print capturing Eugene’s first spelled words and jokes. Officer Higashida voids his detention recommendation and lifts house arrest; the case pivots toward accidental death with Eugene exonerated.

In the weeks that follow, Eugene leans into communication and joins hangouts with other nonspeakers, while Mia wrestles with unresolved threads: Adam’s possible prostate cancer screening and a blank “Experiment #24” entry in the HQ notebook dated June 23. Adam’s phone hint—“add all H & add all Q”—yields a likely 4750 passcode. Facing a final attempt that will auto‑wipe, Mia chooses uncertainty over proof, triggering deletion to protect Eugene from future doubt. On the hundredth day, which coincides with Chuseok, the family holds a memorial at the falls. Beforehand, Mia burns her written account and scatters the ashes over the cliff, a symbolic message across time that Eugene survived and now has a voice. She unveils a large touchscreen letterboard so Eugene can speak more independently. The mystery remains officially unresolved, but the family turns toward connection and forward motion, choosing faith over the completeness of evidence.