After meeting and while working together tending sheep over a summer, Jack and Ennis slowly become close friends then fall in love, keeping their confusing and inconvenient (Ennis is engaged to be married) love affair a secret. Four years later, Ennis is married and has two children. Jack is married and has one. They reconnect and a 20-year love affair is rekindled and lasts through the trials and tribulations of both men.
It's a story told dozens of times. Two people are married to spouses they are not truly in love with, longing for one another, but unable to be together because of societal prejudices. Sirk tackled it with All That Heaven Allows; Haynes with Far From Heaven; it's a time-honored (and weathered, perhaps) tradition.
But Ang Lee plants this story dead set in the middle of the Western genre, a tactic that (thanks to the terrific source material by Pulitzer Prize-winner Annie Proulx) pays off tremendously. Jack and Ennis must escape to Brokeback whenever they decide to get together. Lee dwarfs them in these moments by the bigness of their surroundings. It could be seen as pretty pictures just for pretty's sake, if not for the viewers' knowledge that only in such a remote place as this vast wilderness could Jack and Ennis live out their life together, something Jack has difficulty with almost from the beginning.
In the rest of the film, for the most part, Lee sticks with medium and close shots, keeping things closed in and intimate, even when they grow uncomfortable (especially with Ennis' troubling home life, and Jack's clashes with his father-in-law).
Brokeback Mountain devastates in its moments of quiet solitude and poetic beauty, culiminating in a wondrous denouement, a kind of reverse-mirror-image reflection of the closing moments of John Ford's The Searchers. Because, after all is said and done, Lee has crafted one of the best Westerns I've ever seen, as well as one of the most subtley crafted love stories.
This is the best film of the year.