It stars Tom Hardy and Joel Edgerton as two estranged brothers whose entrance into a mixed martial arts tournament makes them come to terms with their lives and each other.

Real-life MMA and combat sports figures like Kurt Angle, Nate Marquardt, Anthony Johnson, Roan Carneiro, Yves Edwards, Amir Perets, and Dan Caldwell make appearances.

A melancholy U.S. Marine Thomas "Tommy" Riordan visits his father, Paddy Conlon, a recovering alcoholic who has returned to his Catholic faith in Pittsburgh, Pennsylvania.

The next day, Tommy enters a gym where he quickly knocks out Pete "Mad Dog" Grimes, one of the world's best middleweight fighters; a video of the fight goes viral on the Internet.

Tommy's older brother Brendan, a high school physics teacher and former MMA fighter, is struggling to provide for his wife, Tess, and their two daughters.

In the semifinals, Tommy is matched up with Mad Dog Grimes, knocking him unconscious almost immediately, and the commentators claim this is one of the fastest knockouts in MMA history.

In their review, Common Sense Media cites unconditional love as a major theme, further explaining that "some weighty issues" such as estrangement and alcoholism are also dealt with.

"[6] Simon Miraudo from Quickflix praised the character development of brothers Tommy Riordan and Brendan Conlon: "When they speak to each other for the first time in the film – amazingly, only once before they actually meet in the ring – we understand their relationship completely."

[4] Common Sense Media's Sandie Angulo Chen called the film "a touching family drama wrapped in an intense 'David vs. Goliath'-style fight.

"[7] Meanwhile, Roger Ebert gave the film 3 out of 4 stars, declaring that "this is a rare fight movie in which we don't want to see either fighter lose," while praising Gavin O'Connor's direction and Nick Nolte's performance.

[20] Peter Travers of Rolling Stone was also complimentary towards O'Connor, stating that he "comes out swinging in this flawed but fiercely moving family drama,"[21] while A.O.

Scott of The New York Times credited the film for being "appropriately blunt, powerful and relentless," also praising the "skillfully staged" fight scenes.

[22] Andrew Pulver of The Guardian rated the film 2 out of 5 stars stating, "This mixed-martial-arts fight movie has received bafflingly high praise considering its lunkhead plot and rudimentary characters".

"[24] Some critics, including Philip French from the UK magazine The Observer, have noted similarities to other sports drama films such as Rocky (1976), The Wrestler (2008), and The Fighter (2010).

An alternative extended version of "About Today" by the indie rock band The National was also featured on the soundtrack and also in the film during the final fight scene.

[26] The film had an Indian adaptation titled Brothers (2015) starring Akshay Kumar and Sidharth Malhotra in lead roles.