Matthias is a priest in Jerusalem and he has 5 sons. The middle one is called Judas, and nicknamed Maccabeus, which leads me to believe he might become important later. Anyway, Matthias laments all the sinning going on in Jerusalem and he and his sons put on sackcloth.
At the same time, the king's men arrive in a city called Modin and try to make the people there sacrifice. The people go to Matthias for help. The soldiers praise Matthias and co. and ask them to make the fist sacrifice. They promise if they do, the king will like them. But Matthias refuses. As he's speaking, a Jew comes up to the altar to make a sacrilegious sacrifice, which makes Matthias' kidneys tremble, so he kills the guy right there on the sanctuary, along with the king's commissioner. For good measure, he breaks the altar. Then he shouts so all can hear Whosoever is zealous of the law, and maintaineth the covenant, let him follow me. (v. 27). Then he and his sons flee into the mountains, and some of their followers head for the wilderness.
When the king's garrison in the city finds out what happened, they go looking for Matthias' party and surround them on the sabbath day. They promise that those who agree to come back and obey the king will be pardoned, but they won't come out because it's the sabbath. So the king's men attack, but the Jews refuse to fight back, and a thousand of them die.
Matthias' group hears about this and mourns, and they all agree that if they don't fight, they'll all die. So they decide to fight, even if it's the sabbath.
Now a group of Assideans, a sort of fighting yeshiva student, shows up, along with a bunch of other refugees. They slay the sinners and the wicked, but some get away and join the heathens. So Matthias and his new army go around pulling down the altars and circumcising children and avenging themselves on sinners.
They do this for awhile, long enough for Matthias to get old. As he's dying, he passes his crusade on to his sons and tells them the story of the Old Testament again. He appoints Judas Maccabeus as the leader, then dies at age 146.