During what stage of the plot structure does this event occur?

They would be on him any minute now. His mind worked frantically. He thought of a native trick he had learned in Uganda. He slid down the tree. He caught hold of a springy young sapling and to it he fastened his hunting knife, with the blade pointing down the trail; with a bit of wild grapevine he tied back the sapling. Then he ran for his life. The hounds raised their voices as they hit the fresh scent. Rainsford knew now how an animal at bay feels.

He had to stop to get his breath. The baying of the hounds stopped abruptly, and Rainsford's heart stopped, too. They must have reached the knife.