After the success of the 1941 version, Warner Bros. weren't eager to let the 1931 version (or the 1936 attempt, Satan Met a Lady) be confused with it, hence selling it to television under the title "Dangerous Female," an utterly generic moniker. And yet, anyone familiar with the book or '41 version would quickly surmise what they were watching after only a few minutes because the 1931 is very faithful to the novel, much like the 1941.
Two faithful adaptations of a novel; yet, one fell into obscurity and remains there, only really of interest because the novel and '41 version have such devoted fans. Here's my take on the '31, directed by Roy Del Ruth:
After depicting San Francisco's streets, the film opens on the silhouette of a woman kissing Sam Spade; leaving the office, she straightens her stockings. From the start, you can see the difference in sexuality back in the pre-code days - this is a much sexier film than the '41 and in that way, much truer to the original book.
However, the first bit of bad news is Sam Spade himself - played by actor Ricardo Cortez. As I've found in all the 30s films I've seen of him, Cortez is a grinning, snide twerp. Although he has much of the same dialogue in this film as Bogart in '41, he doesn't project any of Bogart's vulnerability - nearly all of his lines are spoken through a grin - or a sneer. Unlike the '41's Spade whom we can see is taking awful risks as he tries to solve his partner's death and keep both the police and the killers off his back, Cortez's Spade is supremely confident and never at a loss - right there, the '41 wins, game over.
Still, let's keep going. After sending his female client away and idly romancing Effie (Una Merkel, easily cuter than '41's Lee Patrick, though Satan Met a Lady's Marie Wilson out-cutes them both and is the best part of that latter film), he enters his office and has his next client ushered in: Ruth Wonderly (Bebe Daniels, in fine form). During his interview, he's interrupted by a phone call from Iva (Thelma Todd), his partner's wife. Four women in as many minutes! Unlike Bogart's later performance, this Spade is unambiguously a womanizer.
At this point, another key difference between the '31 & '41 appears: while the '41 tells everything (except Archer's death) from Spade's perspective, this film takes occasional detours to feature scenes without Spade. Here, Archer (Walter Long) arrives in the office and eavesdrops on Spade's conversation with Iva. So, he knows about Sam & Iva's affair. What does this mean? Well, if you know the story, Jack all - Archer dies in the next scene.
After Archer's death (in this version it happens off-screen), Spade journeys to the murder scene but declines to see the body; he pauses for a moment to hold a conversation with a Chinese man, but as it's conducted in faux-Chinese we aren't privy to the details (this is a huge alteration to the story, in fact, and completely changes Spade's character). Later, the police drop in on Spade; "Come on in, Precious," Spade reacts to their knocking. "Who were you expecting, darling?" Lt. Dundy (Robert Elliott) wonders. "You, sweetheart," Sam mockingly replies. Somehow these jibes are enough to convince the author of this film's wikipedia page of "homosexual themes" and categorizing it as "LGBT-related." Not so much.
From there, the film proceeds as you would expect, up until the introduction of Joel Cairo; Effie introduces him to Spade with: "It's a gorgeous new customer! A knockout!" Like the earlier byplay with Lt. Dundy, it seems to be more that characters mock Spade's constant womanizing rather than the original homosexual content. Going by "Dr. Cairo" here, Otto Matieson can't hold a candle to Peter Lorre; outside of Effie calling him "gorgeous" there's no hint of the homosexual character from the novel or the '41 version - he's a stock villainous character with some better-than-average dialogue, but removing Cairo's effeminate, dandyish behaviour renders it all one-note.
The next point of interest arises after Spade chases Cairo from his apartment; as in the novel, at this point Spade and Wonderly spend the night together; Daniels, whose outfits as Wonderly show here a lot more exposed skin than Mary Astor in '41, also gets to lounge about Spade's apartment barely-dressed. Advantage: pre-code!
Eventually we get to the scenes with Gutman, which are a major highlight in '41 thanks to Sydney Greenstreet; however, Dudley Digges is nowhere near as funny or imposing, capturing none of the conflicted emotions in Greenstreet's portrayal. There's also another scene bereft of Spade as Gutman leaves Spade to converse with Cairo; learning from Cairo that Spade doesn't have the Maltese Falcon but, spelling out exactly where it is (with Captain Jacoby - something the '41 version gets a bit muddled), Gutman drugs Spade's drink so he can take back the advance he paid him. On the one hand, acting out the drugging of Spade from Gutman's perspective isn't good drama; on the other hand, making it clear Cairo & Gutman are working together and the significance of Captain Jacoby are major wins; call it a tie.
There is a just a little too much exposition as the film nears the ends and all loose ends are tied up; Wilmer (Dwight Frye) never has a chance to demonstrate the ineptitude of 41's Elisha Cook Jr (though Spade does call him Gutman's "boyfriend"). They do, however, retain the scene from the book where some of Spade's money goes missing and he demands Wonderly strip for him (another chance for Daniels to lose her clothes); the '41 version keeps everything but the strip search itself intact, instead having Spade quickly deduce Gutman palmed his missing money.
The big problem arrives at the climax as Spade tells Wonderly he's going to turn her in for the murder of Archer. None of the furious indignation found in '41's Bogart performance remains here - Cortez smirks through the entire thing, like he's playing a joke on her. While most of the dialogue is intact, they unfortunately lose much of the great climatic lines as he expresses why he won't "play the sap" for her. Spade turns Wonderly over the police who - unbelievably! - let her stroll out of the building before following her. Uh, shouldn't you put some handcuffs on the accused murderer?
Although the '41 film basically ends here, the '31 adds some problematic additional scenes. First, a newspaper headline establishes the Chinese man Spade questioned identified Wonderly as Archer's killer. This doesn't work at all - why would Spade have bothered playing along with Wonderly when he had a witness to her as the killer and could have turned her over the police before Cairo & Gutman became involved? It casts all of Spade's actions in the film in another light when he knows - not suspects, knows - who Archer's killer is all along.
Problematic scene#2 involves Spade visiting Wonderly in jail and revealing he's working the d.a.'s office; they basically rehash more of the same dialogue from their last scene together, but without any passion. It closes with the revelation Spade has been secretly sending her aid in the prison. Why, he really does care for her! No, this scene isn't needed. The original book and the '41 film present Sam as being conflicted - yet rather dismissive of Wonderly in the climax. Adding a bonus scene to soften up Spade is a waste of effort.
With a different male lead, this could have been pretty good - Hammett's plot and dialogue are mostly intact, after all. It's better than most detective movies circa '31 were, but... well, '41's the Maltese Falcon set the standard by which all detective films are judged; the '31 is a victim of history.