Kristen walks in on Sebastian attacking Emily in Cambodia and strikes him over the head with a lamp, killing him.

Emily and Kristen secretly transport Sebastian's body to a cliff and push it into the river below.

On the last night of a Chile vacation, Kristen flirts with a stranger named Paolo and takes him back to the hotel room.

Emily returns to the hotel to find Paolo dead on the floor and Kristen crying, claiming he attacked her.

Emily and Kristen drive Paolo's body to a remote desert area and spend five hours digging a grave.

Back in Milwaukee, Aaron surprises Emily with an airport pickup when her plane lands from Chile.

Weeks after Chile, Kristen unexpectedly shows up at Emily's front door with news that she was fired from her job.

Chilean authorities discover Paolo's body and launch a murder investigation with American law enforcement involvement.

Kristen reveals she has a photo of Emily and Sebastian together and threatens to send it to authorities.

An online search reveals that Kristen's childhood friend Jamie died by suicide, not in an accident as Kristen claimed.

Emily realizes Paolo's death happened the very night she rejected Kristen's backpacking plan and told her about Aaron.

Kristen appears uninvited in the lobby of Emily and Aaron's Phoenix hotel, sparking a public confrontation.

Emily pushes Kristen off a cliff edge during their heated argument outside the Phoenix hotel.

Aaron's car swerves to avoid hitting Emily in the road, strikes Kristen, and goes over the cliff.

After the case against Emily is dropped, she and Aaron travel to Tbilisi, where she introduces herself as Joan.

Two best friends cover up a death in Cambodia, vowing never to speak of it again. When the same thing appears to happen a year later in Chile, Emily helps Kristen conceal another body in a remote desert grave. As Emily tries to rebuild her life in Milwaukee, Chilean authorities close in and Kristen's behavior grows dangerously controlling. Emily begins to suspect Kristen staged Paolo's death to trap her in a permanent bond of shared guilt. A violent confrontation in Phoenix ends with Kristen's death and Emily facing a criminal investigation. After a lawyer helps Emily craft a careful statement, the case is dropped and she walks free — though the final scene suggests she may carry more of Kristen's legacy than she realizes.

The deadly secrets Emily and Kristen bury — and can't outrun.

Kristen goes to Emily's shared apartment and collects all her belongings so Emily never has to face abusive Ben again.

At a Chile dinner, Emily declines Kristen's proposal for a six-month multi-continent backpacking trip together.

Emily confesses to Kristen during the Chile trip that she has been secretly dating a man named Aaron.

At a Chile bar, Kristen introduces herself and Emily to Paolo using the same fake names they used in Cambodia.

Before checking out of the Chile hotel, Emily and Kristen scrub the blood from the room using makeup removal wipes.

Struggling to cope after Chile, Emily sees a therapist named Adrienne for the first time.

Emily and Aaron have sex for the first time, and Emily abruptly leaves when an urgent-sounding text from Kristen arrives.

On Emily's birthday, Kristen engineers an elaborate scavenger hunt that involves recruiting Aaron and Emily's boss.

While handing Emily her phone to choose music, Kristen accidentally reveals a text confirming she has leased an apartment near Emily's home.

Nana emails Emily a CNN article reporting that authorities have discovered Paolo's remains in Chile.

Emily discovers that the therapist Kristen saw as a child runs an institute exclusively for court-ordered children.

Aaron tells Emily that Kristen privately warned him Emily was trying to get over having hurt someone in Chile.

Emily leaves Adrienne's therapy office only to find Kristen sitting in the waiting room, claiming Priya referred her.

After the Phoenix cliff incident, Emily gives police a carefully worded statement that omits her fight with Kristen.

Investigators confirm Rohypnol was found in Kristen's toiletries bag and that she was fired for shoving her boss.

Long before Chile, Kristen proved her loyalty by rescuing Emily from an abusive boyfriend, creating a debt Emily never forgot. In Chile, Emily's quiet confession about Aaron plants the seed of Kristen's deadly jealousy. Back home, Kristen inserts herself into every corner of Emily's life — her therapy, her birthday, her neighborhood. Emily pieces together the truth about Kristen through a series of smaller but telling discoveries, from a suspicious therapist's institute to a hidden apartment lease. A carefully worded police statement and mounting forensic evidence eventually turn the investigation firmly toward Kristen. The final revelations about Rohypnol and a violent workplace incident confirm that Kristen had a long, concealed pattern of dangerous behavior.

The friendship under pressure — escalations, intrusions, and cover-ups.

Emily and Kristen form a close friendship after realizing they are the only two women in their college economics class.

At a Cambodia bar, Emily and Kristen give Sebastian fake aliases before Emily takes him back to their hotel room.

While scouting the remote burial area alone in the dark, Emily fears that Kristen has abandoned her in the desert.

Emily calls Kristen after returning home from Chile and finds her disturbingly upbeat and unbothered by Paolo's death.

Adrienne tells Emily that some people deliberately create caregiving dynamics in friendships as a disguised form of control.

Emily re-reads her old breakup texts with Colin and realizes Kristen effectively dictated every message she sent him.

An antiques store owner tells Emily she looks strikingly like Kristen's late childhood friend Jamie.

Emily sneaks to the lake house basement and finds childhood photos of Jamie with her face violently scratched out.

Kristen mentions offhandedly that her mother was not originally supposed to be home on the night of the house fire.

Nana begins trying to tell Emily something private beside her car but stops abruptly when Kristen walks up.

Kristen discovers Emily's open laptop showing research on Jamie's death, the house fire, and therapist Lydia Brightside.

Kristen insists repeatedly that it was Emily, not Kristen, who kicked Sebastian to death, and Emily begins to believe it.

After immediately regretting the push, Emily reaches down and pulls Kristen back up from the cliff's edge.

Jenny Rusch reveals that Jamie set the house fire herself, intending only to kill Kristen's sexually abusive father.

Aaron wakes in the hospital and tells Emily he drove to find her after recognizing Kristen in a news police sketch.

Emily and Kristen's friendship began with a sense of rare solidarity, but its foundations were always built on Kristen's need for control. A series of quiet revelations gradually expose the truth about Kristen's past: scratched-out photos, a suspicious house fire detail, and a childhood friend whose death was far from accidental. As Kristen begins rewriting Emily's memories of Cambodia, Emily faces a terrifying question about her own capacity for violence. A single impulsive push at a cliff's edge forces Emily to confront who she really is and what she is capable of. Jenny Rusch's devastating account of Jamie's death finally explains the childhood trauma that shaped Kristen into who she became. By the end, Emily has answers — but the final scene leaves her own transformation disturbingly unresolved.