Raoul Walsh’s 1932 film “Me and My Gal” almost defies synopsis. In less than 80 minutes, a young cop, portrayed by a young Spencer Tracy at his most winning, rescues a drunk from drowning in the East River, makes time with a saucy waitress at a waterfront chowder house, becomes embroiled in a bank-robbing crime spree, foils a bizarre subplot involving a paralyzed pensioner held hostage, and, eventually, hears wedding bells.

There’s real chemistry between Tracy and his co-star, Joan Bennett, and risqué, witty banter galore. There’s also an ingeniously staged and shot bank heist that presages the one in Jules Dassin’s 1955 cops-and-robbers classic,”Rififi.” “Me and My Gal” is the kind of movie that moves effortlessly from romantic comedy to crime picture to melodrama and back again without ever testing credulity or ceasing to entertain. In other words, it’s the kind of movie they don’t make anymore — certainly not at Rupert Murdoch’s 20th Century Fox.

Beginning tonight, Film Forum will present three weeks of films from the Fox Film Corporation and 20th Century Pictures, the two studios that would merge to become 20th Century Fox under 20th Century Pictures honcho Darryl Zanuck in 1935. The program, compiled by Film Forum’s reliably ingenious programmer, Bruce Goldstein, is the latest look at Hollywood’s “precode” era (roughly between 1929 and 1934), when, in an attempt to win back Depression audiences, Hollywood producers added as much sex and sin to their pictures as they could get away with. Of course, they didn’t get away with it for long: With various pressure groups calling for boycotts of movie theaters showing “smut,” Hollywood caved in and in 1934 adopted a strict Production Code of Ethics, stating that “no picture shall be produced which will lower the moral standards of those who see it.”

But these films aren’t just sin-fests. The program also boasts gems like Tracy’s debut as a leading man (1931’s “Quick Millions”) and the great Clara Bow’s swan song (1933’s “Hoopla”). It contains films by lauded auteurs Fritz Lang (the rarely revived and underpraised “Liliom”), Raoul Walsh, and Frank Borzage, and two of the three extant films by Rowland Brown, one of the most unjustly obscure writer-directors to ever wear both hats. “Fox Before the Code” isn’t just a celebration of postjazz-age hot pants, blazing guns, and tough talk, but a remarkable tribute to an era when the Hollywood dream factory would stop at nothing to entertain.

With the Great Depression in full swing, early 1930s Hollywood could only hold back reality so much. Meanwhile, sound had turned filmmaking upside down after “The Jazz Singer’s” surprise box-office breakthrough in 1927. The talkies‚ with newfangled technical requirements — camera immobilizing microphones and soundproofing — initially discouraged the pure visual communication and experimentation that flowered so spectacularly in mid-1920s American cinema.

Like the competing studios, both Fox Film Corporation and 20th Century Pictures combed New York and Chicago for writers who could craft dialogue that would keep pictures moving even if the camera couldn’t. Philip Dunne, one of four uncredited writers who worked on Walsh’s “Me and My Gal” (1932), came West to relieve both chronic sinusitis and chronic unemployment. Dunne helped polish the hash house banter of “Me and My Gal” and lent the film a curbside New York feel that supports the movie even today.

“The Bowery” (1933), the other half of this weekend’s double bill and one of four Walsh pictures in the retrospective, has a pre-code allure all its own. The late film historian and teacher William K. Everson (to whom “Fox Pre-Code” is co-dedicated) used to introduce “The Bowery” with the observation that “this film insults more ethnic groups in the first five minutes than most films do in an hour and a half.” But “The Bowery” is much more than an explosion of pre-PC permissiveness. Like “Me and My Gal,” it’s a wonderfully off-the-wall stylistic stew. The film folds together abject cynicism, romantic self-sacrifice, male bonding, gleeful violence, and lurid back-alley exposé into a soot-covered movie confection of the first order.

Upon its original release, “The Bowery” was a hit and an auspicious start for Zanuck’s 20th Century Pictures. Despite being crowned production head of Warner Bros. in 1931 at the ripe old age of 29, the future-minded Zanuck realized that the studio had a glass ceiling in place for anyone not named Warner. Using his highly bankable box office track record as investment bait, Zanuck set out his own shingle and made a studio in his own image at 20th Century. Though history tends to marginalize him as perhaps Hollywood’s most prodigious cultivator of yes-men and most shameless user of the casting couch, Zanuck saw himself as a writer. He looked for the same workaholic habits and story construction instincts that drove his own work in the work of those he hired. That trust paid off in the form of Rowland Brown.

A newspaper-man-turned-film-scenarist at Fox who had, according to Phillip Dunne, “an affinity for the underworld,” Brown directed his debut, 1931’s “Quick Millions,” with only three produced scripts to his credit. “Take your elbow out of my ribs,” Spencer Tracy says to ruthless trucking racketeer “Bugs” Raymond en route to a very different wedding scene than the one that ends “For Me and My Gal.” “That’s not my elbow,” the leering killer sitting next to him replies. Clever dialogue in a pre-code gangster picture is a given. “The more ingratiating screen dialogue grows, the more it’s apt to forget its proper place,” warned film critic Janet Graves in the New York Times almost exactly 70 years ago.

What sets apart “Quick Millions,” made for Zanuck at 20th Century (screening in a new print), from better known pre-code gangster mellers like “Little Caesar” and “Scarface” isn’t Brown’s ear for street patois, it’s his assured filmmaking right out of the gate.

Though praised at the time for its frank depiction of crooks and politicians at work with and against each other, “Quick Millions,” has a subtle and expedient visual style decades ahead of its time. Brown, Graves wrote in 1936, “has cut his whole picture to the same economical pattern. The rapid rhythm of its continuity was built up from short scenes; the dialogue was correspondingly laconic. Each scene quietly thrust home a point of character or plot — and stopped.”

Using dissolves, sound bridges, long takes, and character punctuating close-ups, Brown blessed “Quick Millions” with both gutter swagger realism and pulp expediency. It is the most undervalued directorial debut in the history of American film. And like the rest of Film Forum’s wide-ranging groaning board of pre-code freedom, compared to contemporary literal-minded Hollywood and self-congratulatory indiewood fodder, “Quick Millions” is a reminder, not of how much ground American film has gained since the decades between the World Wars, but of how much it has lost.

Through December 21 (209 W. Houston St., between Sixth Avenue and Varick Street, 212-727-8110).