Lady, Stay Dead

Mason drowns Marie after she bites him and calls him an animal during the assault. The combination of her resistance and verbal humiliation triggers his rage, leading him to kill her in a fit of violent anger. He then attempts to hide her body in a garbage bag.

Earlier scenes show Mason obsessively spying on Marie, establishing his unstable fixation before the attack.

Billy catches Mason trying to dispose of Marie's body in a garbage bag. Witnessing this crime, Billy becomes a threat to Mason's freedom, so Mason kills him to prevent him from going to the police. Mason also poisons Billy's dog to eliminate any potential witness or alarm.

Jenny notices multiple unsettling clues: the house feels empty when she returns, she finds Marie's necklace jewels in the fish tank, discovers Billy's dead dog floating at the beach, and finds Billy's body on his couch (initially thinking he's napping). When she meets Mason, his unusually intimate knowledge of the house, combined with a muddy footprint he tried to clean, confirms her growing suspicions.

The timeline shows Jenny making several unanswered phone calls to reach Marie and Billy, building her anxiety before she meets Mason.

Mason becomes obsessed with Jenny as a replacement for Marie. During the final confrontation when he corners her on the highway, he strangulates her while visualizing Marie's face in her place, indicating his psychological breakdown and inability to separate the two women.

Mason plays Marie's song 'Loving from a Distance' and presents gifts to Jenny, mirroring his obsession with Marie.

The film doesn't explicitly explain how Mason survives drowning in the pool. After Collings appears to kill him by holding him underwater, Mason unexpectedly revives, kills Collings, and continues his pursuit of Jenny. This twist serves the film's horror logic rather than realistic explanation.

Collings tries to negotiate with Mason rather than immediately attacking because he wants to safely extract Jenny. He also explains Mason has a history of raping women who never pressed charges, suggesting Mason is dangerous and unpredictable. Collings attempts to reason with him and urges Jenny to flee while Mason won't see her in the dark.

Jenny hesitates because she discovers Marie's body in the backyard while trying to flee. Rather than running immediately to safety, she stops to mourn her sister, which delays her escape and gives Mason additional time to pursue her.

'Loving from a Distance' is Marie's favorite song that Mason plays on the radio during the assault. The song becomes his twisted theme, and he later whistles it while taunting Jenny at the motel and cutting the phone line, symbolizing his obsessive fixation and the emotional distance he perceives from the women he stalks.

The motorcyclist happens upon the attack on Jenny and hits Mason with his vehicle, flinging him into Collings' car. This random act of intervention ends Mason's rampage. The motorcyclist likely acted instinctively to stop the violent assault he witnessed.

Yes, Jenny survives. After Mason corners her on the highway and begins strangling her, the motorcyclist hits Mason, preventing him from killing her. She is later found lying on the road by arriving police officers. While she survives, the ending is somber given the deaths of Marie, Billy, and both police officers.

Mason kills Dunbar (referred to as 'Pops') when the officer attempts to radio for backup. Using a shotgun, Mason eliminates Dunbar before the policeman can alert others or provide reinforcements, removing a threat to his freedom and allowing him to continue his pursuit of Jenny.