In the very beginning, this Mayan tribe that Jaguar Paw (Rudy Youngblood) is a part of, is hunting a wild boar. Together with other tribemate, his father, and his brother, then force this pig into a trap that slams spikes into the boar. As they are celebrating the kill, another tribe wanders by only asking for permission to pass. The presumed leader of that passing tribe warns Jaguar Paw that they are fleeing because their campsite was invaded.
On the way back to camp, Jaguar Paw's father warns Jaguar Paw that he saw the fear in his eyes when they were told that the other tribe's camp was invaded. The father gives Jaguar Paw a pep talk about not having fear. That night, the tribe gathers together to hear the elders give a spiritual talk that Jaguar Paw really takes to heart. The next morning, Jaguar Paw, and his wife who is visible pregnant, are awoken by a loud barking dog. When the dog stops barking (because it was killed by an invading tribe) Jaguar Paw becomes suspicious why the dog stopped barking. He sees an invading tribe member with a torch run by and he wakes up his wife and son and they begin to run for cover as the invading tribe kills many men and rape the women while leaving the children unharmed.
Jaguar Paw takes his wife and son to a cave and lowers them into it for safety. An invading tribesman sees Jaguar Paw at the top of the cave and begins to charge to try and kill him. Jaguar Paw fights back and kills him. Even though his wife begs and pleads with him to climb down and be safe, Jaguar Paw's pride takes over and says that he has to help the others and he promises he'll be back. He manages to take out a guy or two, and just as he's about to kill another, the headmaster of the invading tribe stops the fighting. All the men and women of Jaguar Paw's tribe is taken prisoner. Jaguar Paw's father is killed right in front of him after Jaguar Paw accidentally reveals to the invading tribe who his father was. This one member of the invading tribe, seemingly the second in command, takes a liking to Jaguar Paw and deems his new name as "Almost" signifying that Jaguar Paw "almost" killed that guy.
The men and women are sent on a death march to the invading tribe's home camp. Jaguar Paw sees the presumed headmaster of the tribe that was asking for permission to pass earlier in the movie, has also been taken prisoner. Along the way, the run into a little girl who is believed by the tribe to be diseased. When she is denied help, she forewarns and foreshadows that the invading tribe will decline at the hands of a man who knows the jungle and that day will turn into night. When they get to the new camp, the women are sold as slaves and the men are forced to walk up this temple to be used as sacrifices.