Marlowe doesn’t run into Canino or Art as he goes back to his car in the pouring rain. He thinks about Mona, who hid to protect Eddie, whom she loves. He also thinks through how Canino likely planned to kill him, while not letting Mona find out.
Marlowe’s train of thought, that Canino wouldn’t think twice about killing him and lying to Mona, emphasizes this is a fight for survival against a known murderer.
Making it to his car through the driving rain, Marlowe finds that Art had fixed it, leaving it as another getaway car option. In his car, Marlowe gets his hidden gun out, and has to quickly hide to avoid the headlights of Canino’s returning car.
Having prepared for every eventuality, Marlowe runs back to his car to get his stashed gun. Art and Canino have also planned for all outcomes, preparing a second getaway car just in case.
Marlowe gets his gun ready at his side, as far round as he can reach it, and walks back toward the house. He climbs into Canino’s empty car and turns the ignition, the motor sounding through the night. Marlowe then gets out of the vehicle and hides down behind the back of the car.
Marlowe’s determination to survive is coupled with his wide-ranging abilities, which stretch to being able to hold a gun while handcuffed behind his back. This depicts Marlowe as a physically adept man’s man.
Canino opens one of the house’s windows and fires three gun shots into the driver’s seat. Marlowe yells in fake pain. Canino laughs from inside the house.
Baited into Marlowe’s trap, Canino believes he has the upper hand, or has even killed Marlowe. Again, Marlowe remains in total control of a potentially chaotic situation.
The front door opens, and Mona steps out, with Canino holding a gun to her back. Mona screams and says she can see Marlowe behind the driver’s wheel. Canino pushes her over and fires three more times into the driver’s seat.
The author emphasizes Canino’s evilness as he holds a gun into an innocent woman’s back, firstly making it clear who stands on the wrong side of the moral/immoral line as Canino uses Mona as a human shield, and secondly leaving no doubt that Canino intends to kill.
Marlowe gets up and calls Canino, who faces him. Marlowe shoots him four times and Canino falls to the ground, dead. Standing near Mona now, Marlowe begins to laugh maniacally. Mona asks if he had to kill Canino, stopping Marlowe’s mad laughter. She gets the key and undoes Marlowe’s handcuffs, saying she guesses he did have to kill Canino.
With Canino fully established as the villain, Marlowe killing him is an unquestioned victory. Despite the fact killing Canino can be considered justifiable, the act still has an adverse psychological effect on Marlowe, who temporarily loses reason. Although he has survived, the detective is now a killer, as Mrs. Regan had accused him of being earlier.