In Dashiell Hammett's novel The Maltese Falcon, how did Brigid O'Shaughnessy expect Floyd Thursby to be caught?
Brigid wanted Thursby to be suspected of killing Miles Archer because his gun would be found at the murder scene--but how did she expect the police to know it was Thursby's gun or even that he was in San Francisco? How would they know where to find him in San Francisco?
In Chapter 20 titled "If They Hang You," Spade tells Brigid O'Shaughnessy:
"You thought Floyd would tackle him and one or the other of them would go down. If Thursby was the one then you were rid of him. If Miles was, then you could see that Floyd was caught and you'd be rid of him. That it?"
"S-something like that."
Evidently Brigid had been planning to make an anonymous phone call to the police and give them Thursby's address along with the tip that he had killed Miles Archer. But when she pointed out to Thursby that he was being tailed, Thursby failed to do what she hoped. So she killed Archer herself, as Spade has deduced, and intended to call the police and tell them anonymously that Thursby had done it and where they could find him. However, Thursby himself was killed by Wilmer Cook right in front of his hotel on Geary Street. Where was Brigid at that time? When did she find out that Thursby had been killed? Did she plan to call the police the same night she killed Archer? Or did she plan to wait until the next day? Did she read about Thursby's murder in the next morning's newspaper? Or did she have some other way of knowing that he had been killed?
If she read about Thursby's murder in the newspaper, did she still go ahead and phone the police? Or would she be afraid of being connected with Thursby's murder? She apparently didn't know much about his criminal record. She couldn't be sure the police would connect Thursby with Archer's murder in Burritt Street because she couldn't be sure the police would connect the Webley-Fosbery automatic revolver with Thursby. She could assume that Sam Spade would tell the police his partner had been tailing a man named Floyd Thursby, whom his client had told him was a gangster and a dangerous man. She couldn't assume that the police would know where to find Thursby, though, unless she tipped them off.
But Brigid had bigger worries. When Thursby was shot down, she realized that Casper Gutman was in San Francisco and would be looking for her. She was taking a big risk in contacting Sam Spade for protection, since he was Archer's partner. Why not go to some other private detective? Maybe she thought she was above suspicion. She must have thought the police would not investigate Archer's murder because they would assume Thursby had killed him. Otherwise, if the police had asked questions all over the area around Burritt Street they could have found apartment-dwellers who had heard a shot and perhaps even one or two who had seen a woman exiting the blind alley into Bush Street right after the shot was heard! At the scene of Archer's death, Spade asks Sergeant Polhaus:
"Didn't anybody hear the shot?"
"For the love of God, Sam, we only just got here. Somebody must've heard it, when we find them."
Maybe Brigid went back to Spade, rather than seeking help elsewhere, because she wanted to be able to keep an eye on him. If she can get him to help her, with money or love, she can keep him from telling the police anything about her.
In Chapter 15 we learn that the police connected the Webley-Fosbery to Thursby at Thursby's hotel. Tom Polhaus tells Spade while they are having lunch:
"We got hold of a kid--a bellhop at Thursby's hotel--that had seen it in his room just that morning."
It would have been easy, of course, for the police to find out where Thursby was living. Wilmer Cook made that a simple matter by shooting Thursby just as he was going into the hotel. Evidently Thursby was registered under his real name.
Dashiell Hammett never explains how Brigid got hold of Thursby's gun. Spade says:
"And when you found that Thursby didn't mean to tackle him you borrowed the gun and did it yourself. Right?"
"Yes--though not exactly."
Did she literally ask Thursby to lend her the Webley? How could she explain why she needed his gun? When she says "...though not exactly," she must mean that she had access to Thursby's hotel room and took it when he wasn't there. He has two guns, according to what Brigid tells Spade, so he must have been carrying his other gun the night he was killed, if he was carrying a gun at all. If he wasn't carrying a gun, that could explain why he didn't tackle Miles Archer.