Marlowe meets Agnes in a parking lot, where she tells him that Mona is hiding out east of Realito, in a house next to a small garage run by a man named Art Huck. There's a cyanide plant nearby, and the house is just off the highway.
Agnes had accidently discovered Mona's hideout one day when she and Brody were driving. They saw Canino in a car with Mona so they tailed her.
Marlowe drives toward the location described by Agnes. It's still raining. As Marlowe nears what looks like a small garage, his car runs over some tacks and he gets two flat tires.
Not good. He sees a light coming from what he thinks is Art Huck's garage. Canino's car is in the driveway.
Pretending he needs new tires, Marlowe knocks on the garage door. Art reluctantly lets Marlowe inside, where Canino is waiting.
Canino orders Art to go fix Marlowe's tires and then offers Marlowe a drink. There doesn't appear to be any cyanide in the glass, but when Marlowe isn't paying attention, Canino and Art attack him and Marlowe's knocked out cold.
Fun project: Count the number of times that Marlowe has to resort to violence or is the victim of violence. Compare this to a detective like Sherlock Holmes, who rarely has to get down and dirty to solve a crime. Now imagine if Marlowe and Holmes had to join forces on a case, who'd solve it first? Pretty mind-blowing, right?