Setanta was the son of the King of Dundalk. He wanted to join the Red Branch Knights in the service of King Connor of Ulster; he travelled to Armagh. One day Connor, his knights and Setanta were invited to a feast by Culann, the chief smith of Ulster. When it was time for the feast, Setanta was in the middle of a hurling match. He decided to go to the feast when the game was finished.

When he arrived the feast had already started and the gate was closed.Setanta could hear the sounds coming from the feast and he decided that he would not disturb Culann. He climbed over the gate and jumped down. He was looking around him when he heard a loud snarl and a growl. He turned quickly and saw a huge wolf-hound towering over him, with its teeth bared and its eyes gleaming. It was getting ready to spring at him.

Setanta threw his hurley at the hound, but it did not seem to notice. Then the dog sprang, with its large mouth open ready to kill the boy. He took aim and threw his hurling ball down the dog's throat. That gave him a moment. He grabbed the dog by the throat and began to shake the life out of it, but the animal's nails scratched and tore at him. He could feel blood from the cuts streaming down his body. With a great burst of strength, Setanta crashed the dog's head against the gate and with a loud groan the dog fell dead: Inside at the feast the dog's snarls and growls had been heard. Culann jumped up quickly. `There must be someone breaking into my house. That noise is made by my watch-dog'. Connor suddenly remembered Setanta. He and the Red Branch Knights dashed out expecting to find Setanta torn to pieces, but instead they found him standing over the dead body of the dog. `What a brave, strong boy' said Connor, who was proud of Setanta's strength. Culann was standing in the middle of the crowd. He looked down at the body of his dog and he was very sad because he had loved , his wolf-hound. When Setanta saw how sad Culann was looking, he went over to him. `Do not be sad' he said `I had to kill the dog to save my own life, but we will get another hound who will be just as good. While we are searching for a dog and training it I will guard your home for you'. Culann cheered up when he heard this idea and, from that day on Setanta became Culann's watch dog. He was given the name Cu-Chulainn. This was the name which became famous because it belonged to the greatest hero Ulster had ever known.