Behind the scenes romances are nothing new. The most famous of these is Lauren Bacall and Humphrey Bogart. Bacall was just 19 when director Howard Hawks cast her alongside Bogart in To Have And Have Not and despite the 26-year age difference, the two stars instantly fell in love. The chemistry was immediate and the two married, with Bacall staying devoted to Bogart until his untimely death in 1957. They made four incredible films together from 1944 to 1948, each capturing the greatest romance Hollywood has ever seen.

To Have And Have Not feels like a documentary on how the two fell in love. Hawks and writers William Faulkner and Jules Furthman took Ernest Hemingway's worst book (his words) and molded it into a sort of Casablanca by the Sea. The film has some similarities with that 1942 classic but it is very different since Hawks was always someone who led, not followed.

It tells the story of boat captain Harry “Steve” Morgan (Bogart), who gets wrapped up in helping the French Resistance to smuggle people off the island of Martinique. Harry ends up falling in love with Marie “Slim” Browning (Bacall), a young American spending her time away from home on the island. It's fleshed out with an amazing supporting cast (including Hoagy Carmichael of all people) and unexpected twists, which ensure that the audience isn't just thinking that this is a Casablanca rip-off.

After To Have And Have Not, Warner Bros. put Bacall in Confidential Agent with Charles Boyer, which was critically panned. The couple then re-teamed for Hawks' The Big Sleep. Easily the best of their films together, Bogart stars as Raymond Chandler's famous detective Philip Marlowe and the snappy dialogue is again provided by Faulkner and Furthman with Leigh Brackett.

I never get tired of watching The Big Sleep. For one thing, the film's plot is never clear, which begs for multiple views. It could be one of the most confusing film-noirs ever made, but the chemistry between Bogart and Bacall almost makes you forget that there is a crime Marlowe wants to solve. In fact, the film was re-edited to include more scenes of them together in 1946 to counteract the bad press from Confidential Agent and capitalize on their relationship. The new scenes seamlessly fit in the film, even if it makes the plot even more confusing, but the result was a much better film.

In 1947, the couple made Dark Passage, which was written and directed by future 3:10 To Yuma (1957) director Delmer Daves. The film, based on David Goodis' novel, is another noir, which finds the two in San Francisco. Bogart plays Vincent Parry, you just escaped from San Quentin. He's accused of killing his wife, but as soon as he escapes, he goes on the hunt for the true killer.

Dark Passage was acclaimed thanks to Daves' inventive use of point-of-view. For the first third of the film, we never see Bogart's face, until his character gets plastic surgery. However, the knock on the film is that it isn't Bogart's finest hour. In fact, Bacall, who plays the woman who protects him, blossoms, becoming much more than a pretty face. There's also a fantastic performance by Agnes Moorehead, which helps lift this out of the basement of average noir.

Their final film together is probably the most interesting, John Huston's Key Largo, released in 1948 and based on Maxwell Anderson's play. Coming hot off the heels of their best collaboration, The Treasure of the Sierra Madre, Huston and Bogart got together for one last project for Warner Bros. Bogart stars as WWII vet Frank McCloud with Bacall as Nora Temple, the daughter of hotel owner James Temple, played by the incomparable Lionel Barrymore. Everything seems perfectly fine, until gangster Rocco, played by a deliciously insane Edward G. Robinson, enters the picture.

This is really a film filled with stunning performances everywhere you look. Claire Trevor deservedly won an Oscar for her supporting part as Rocco's drunk girlfriend. Robinson is his typical, over-the-top self, providing a stark contrast to Bogart's more restrained style.

Bogart and Bacall would continue to star in several important films but they would never work together again on the screen, which is a shame. These four films are all very different and important, but they remain rightly known for their ability to catch one of the great love stories to come out of Hollywood.

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