Jack is a greyhound dog trainer living in the woods with his wife, Frances, and his three-year-old son, Joel. While taking the dogs for a walk, they all attack and kill a ground hog. He is always surprised to see how ferocious they are once they are involved in the chase. The dogs start acting aggressively when they see a distant figure behind the trees. Jack believes it a bear, but he finds that it is actually Mark Craeger, an old acquaintance who is almost physically unrecognizable. Craeger is physically deformed and acts in a vulgar manner. He returns to Jack’s home and greets Frances, who is also familiar with him, and meets Joel for the first time. Craeger growls at their dogs to rile them up, and both Jack and Frances are ready to kick him out. He digs up old, vague memories about the time when Frances was in love with him instead of Jack. The only one who seems to like him is young Joel. When Jack threatens to call the police if Craeger continues lingering around, Frances starts to feel bad about kicking him out. Before leaving, Craeger takes a photo albums with pictures of Frances’s pregnancy and reminds Jack that he is Joel’s actual father. As Craeger walks away from their home, Jack takes up him rifle and opens the dog kennel. The first greyhound easily leaps over the run and the rest follow as Jack unkennels them one-by-one. He watches from a distance as they hunt down Craeger and attack him. Jack shoots the dogs on Craeger, and Frances runs out screaming. Jack tells her he killed the dogs and to call the sheriff since Craeger may still be alive.