They went next day, the boy guiding Oisin, holding the dog by a chain. They went first to the place where Oisin had touched earth and lost the magic steed from Tir na n-Og. The borabu of the Fenians of Erin was lying on the ground there still. Oisin took it up and they went on to Glen na Smuil (Thrush's Glen). When at the edge of the glen Oisin began to sound the borabu. Birds and beasts of every kind came hurrying forward. He blew the horn till the glen was full of them from end to end.
"What do you see now?" asked he of the boy.
"The glen is full of living things."
"What is the dog doing?" "He is looking ahead and his hair is on end."
"Do you see anything else?"
"I see a great bird all black settling down on the north side of the glen."
"That's what I want," said Oisin; "what is the dog doing now?"
"Oh, the eyes are coming out of his head, and there isn't a rib of hair on his body that isn't standing up."
"Let him go now," said Oisin. The boy let slip the chain and the dog rushed through the glen killing everything before him. When all the others were dead he turned to the great blackbird and killed that. Then he faced Oisin and the boy and came bounding toward them with venom and fierceness. Oisin drew out of his bosom a brass ball and said: "If you don't throw this into the dog's mouth he'll destroy us both; knock the dog with the ball or he'll tear us to pieces."
"Oh," said the boy, "I'll never be able to throw the ball, I'm so in dread of the dog."