The moment it becomes clear that the opening narration for the film you are about to watch is actually a suicide note, it is obvious that you are about to sit through a dreary, oppressively depressing picture. That's the way Terence Davies' 2011 adaptation of Terence Rattigan's 1952 play The Deep Blue Sea starts and it never lets up. Only buoyed by fantastic performances, the film's gloominess may make it hard to watch, but its exploration of relationships in post-war Britain is too fascinating to look away from.

Set in the early 1950s – Davies makes a point of not nailing down the film's exact date – Rachel Weisz stars as Hester Collyer, the young wife of respected High Court judge Sir William Collyer (Simon Russell Beale). She meets and falls in love with Freddie Page (Tom Hiddleston), a drunk pilot who flew for the RAF during the war. It seems like the glamorous life she had always wanted is finally here. No more appearances to make with the judge or sleeping over his mom's house in different beds. She's suddenly liberated, or so she thinks.

As previously noted, the film begins with her attempt at suicide. Her neighbors rush to stop her. Later, we learn that the tipping point for her behavior was the fact that Freddie had forgotten her birthday. The further details of their relationship are ironed out through flashbacks, but the real drama is in the present. Hester struggles to deal with the free-wheeling Freddie, who can't commit to anything, while William continues to pop in and out of her life, hoping to help her. She wants the rose-colored life with Freddie, but pines for the rigid lifestyle she left behind.

There is no time for joy in Davies' film. While other movies that deal with similar affairs often show the happy moments in the central couple's lives before they are destroyed, Davies only presents brief flashes of happiness. And even in those moments, the truth of Freddie is never far. He only seems to smile when he's at the bar, singing pub songs and drinking with his buddies. Hester herself never seems happy with either William or Freddie. She wants them to be people different from who they really are, which forces herself to live in a constant state of disappointment.

This all makes The Deep Blue Sea a difficult film to deal with. Davies allows for no light, even stylistically. His London is dreary, as if he makes a point of demolishing our romanticized view of the city as it rebuilds after the war. Blueish hues obviously recall the film's title, as if hammering the point that what we are watching are actions at the bottom of the depths of human emotion. Love is one of the most basic emotions we feel – the heart wants what it wants, after all, social convention be damned.

Rachel Weisz's performance was instantly praised when The Deep Blue Sea was released in the U.K. (and in the U.S., where she won a New York Film Critics Circle award). She is quite good here, playing the emotionally fragile Hester as more than just the woman that everything happens to in the film. Sure, the character doesn't seem very interesting on the surface, but that's part of the understated performance Weisz gives and what Davies was looking for. He wants to get the audience to be somewhat surprised when Hester stands up to Freddie and William, but the audience also needs to feel disappointment in her when she struggles to make decisions.

The men in the love triangle are also have to perform well and they are both up to the challenge. Simon Russell Beale and Tom Hiddleston could not be more different. Beale plays the role more restrained, with anger rarely bubbling to the surface. Hiddleston plays Freddie like a ball of energy, wearing his emotions on his sleeve. It helps to contrast the differing generations the two men are from and shows how Hester could fall in love with either of them. It's never clear if her marriage to William was arranged, but it doesn't seem like it was. There's a love between the two, even if it's less clear than the love between Hester and Freddie.

The Deep Blue Sea is a movie anyone has to be in a particular mood for. This is not fun to sit through by any means. But the acting and Davies' throwback filmmaking style produce an adult drama that paints a doomed portrait of love that's impressive. For some, it might test your patience, but if you enjoy well-acted melodramas, this has to be one of the best in recent memory.

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