Borderline plot recap, spoiler-light
Set in 1990s Los Angeles, Borderline follows a violent and deeply delusional sociopath named Paul Duerson who becomes obsessed with world-famous pop star Sofia Minor. After escaping from confinement, Paul targets Sofia and infiltrates her secure mansion. Earlier, Paul had stabbed Sofia's bodyguard Bell when Bell attempted to intervene during an initial encounter.
Months later, Bell recovers and tries to warn Sofia about Paul escaping custody alongside fellow inmate Penny Pascal. Meanwhile, Sofia experiences friction in her personal life after an argument with her new romantic partner, professional basketball player DeVante Rhodes, causing him to briefly leave the property. Shortly after, the home security is catastrophically breached when Penny eliminates a guard while Paul sneaks inside to target Sofia directly.
Concurrently, Paul's accomplice J. H. Calhoun abducts Abby and Eleanor from Bell's apartment, shoots Bell in the head, and drives Abby and Eleanor to Sofia's mansion. Sofia finds herself locked inside her home recording studio booth, setting the stage for a chaotic and dangerous final act driven by Paul's unshakeable, distorted reality.
