I can't see every film out there so this spoiler was sent in and spoiled by: "breadfan87"
In The Skulls, Joshua Jackson plays Luke McNamara, a college student who is low on funds and is desperate to find a way to pay for his future. He gets invited into a secret society, the most powerful of them all, The Skulls. In order to become members, all those invited are to steal a rival society's mascot, and bring it back to the Skulls. When they go to steal said mascot, Luke and another candidate, Caleb Mandrake, take the lead and retrieve the mascot on their own. So, all of the candidates are now skulls, and are assigned "soul mates", or life long partners who you are supposed to do anything for and consider your closest friends.
Things are going fine until one of Luke's friends (named Will) digs a little too deep into what is going on with the skulls, and he winds up dead. Luke eventually finds out that Caleb was responsible for the death of his friend, and so he wants out of the skulls. He and his girlfriend look for the video tape of Will's death, (the skulls home base is covered in security cameras), and when they view it they discover that Caleb left in a panic, and Will was still alive. Senior skull members came into the room and finished him off, snapping his neck. Luke intends to use this tape to blackmail the leader of the skulls, Caleb's dad, but when he brings it to the police to view, it is blank. So, he is put in a madhouse until broken out by his girlfriend, who also happened to be a friend of the recently deceased Will. Well they evade an attack from the same skull member who killed Will, and then decide to use the skulls own rules to bring down the leader. There is a rule that says if a member has a legitimately large problem with another, he can challenge that member to a duel. . . .yes, a duel.
Luke challenges Caleb to a duel in the hopes of swaying Caleb into helping take down his father, who Caleb happens to hate. Luke says that Caleb didn't kill Will, and isn't in as deep as he may think. When they turn to fire, Luke drops his gun and Caleb hesitates to shoot him. Caleb's father is screaming at him to fire, and Caleb is screaming back at his father. Then his father picks up a gun and turns to fire at Luke, but Caleb shoots him first.
The leader is overthrown and a new one takes his place.