The movie opens with a horse grazing in a small clearing in the middle of the forest. He is alerted by an unknown and unseen presence stalking him, which causes him to gallop for the protection of the trees. He is followed by some unknown enemies who are chasing him, before they surround him and prepare to attack.
Meanwhile, a boy and his parents, the last of the summer tourists, are forced to leave their dog behind because they knew that they would be forced to send him back to the dog pound. Later that day, he is found by a pack of feral dogs, most of whom were abandoned pets belonging to summer tourists. Their leader, a massive golden-haired mongrel, immediately accepts the dog into his pack.
Jerry (Joe Don Baker) has moved to Seal Island with his new wife, Millie, and their two sons. They also brought along their family dog, a German Shepherd named Riley. While dropping off some garbage at the island junkyard, Jerry's dog chases after a rabbit into the trees, but is attacked by an unknown creature and is injured. When Jerry goes back to see what it was that attacked Riley, he discovered that it was a feral dog, who had apparently also stole the rabbit that his dog was chasing. He immediately sent word to the other residents on the island, including the old hermit Mr. McMinnimee, to keep a watchful eye out for the dog and kill it if they ever see it again.
McMinnimee, who lives in a cabin alone with his German Shepherd Shazah, soon learns of the wild dog and returns to his home. When a storm hit the island one evening, Shazah starts up a riot and tries to break out. The old man, armed with his rifle, opens the door to his cabin and tries to find out who is intruding onto his property. Shazah bolts out into the front yard, but is suddenly attacked by the golden-haired mongrel plus several feral dogs. McMinnimee is too late to save his dog from the pack, though he manages to shoot and kill a collie, one of the pack members. As he tries to secure the door and windows to his house, the dogs break through one of the windows and starts eating the old man alive.
The following morning, while relaxing in her new house that Jerry had built for her, Millie notices that something is scaring their poultry. She goes outside and discovers the same mongrel that Jerry saw the other day lurking near the poultry yard. She tries to drive it off, but the dog growls at her and attacks, forcing Millie to seek refuge in her Volkswagen car. As the rest of the pack surround the car and try to break in, Jerry arrives and drives the dogs off, killing a Labrador retriever with his shotgun. He takes Millie to town, drops her off at one of the abandoned houses, and warns his neighbor Cobb of the pack. While Cobb leaves to warn the other islanders of the dogs, Jerry picks up his sons and takes them back to the house.
Meanwhile, one of the islanders, Dodge moves to the island with his son Tommy, a cook Lois, and his wife Marge. The day after their arrival, Dodge urges his son Tommy to go for a walk, and Lois goes along with him. During their walk through the forest, Tommy hears the pack of dogs howling nearby and starts running for his life. Lois chases after Tommy, but quickly loses him and is forced to seek refuge in an abandoned barn where the dogs sleep. Tommy runs through the forest, the pack in close pursuit, but soon trapped at the edge of a cliff towering above the ocean. With the savage dogs closing in, he jumps off the cliff and falls to his death.
Lois seeks refuge in the abandoned barn just as a storm hits the island. She lays down in one of the stalls and falls asleep, but when she wakes up, she discovers that the dogs have returned. The dogs growl menacingly before they attack Lois, killing her and eating her corpse.
Meanwhile, Jerry and Cobb manage to warn Walter, Dodge, and Marge about the dogs roaming the island and bring them back to the house. But when Jerry arrives at McMinnimee's cabin to warn him, he believes something is wrong when the old man does not respond. He then discovers the dead bodies of Shazah, and the collie. After searching the side of the cabin, he finds the old man's lifeless body inside having already been attacked and mauled by the pack. Jerry then leaves Mcinnimee's cabin just managing to avoid the pack who had been stalking him. He returns to the house and tells Lois and the others of what had happened. He even states that most of the dogs were once tourists' pets, but were abandoned to survive on the island a few weeks earlier. Dodge, concerned and outraged that his son Tommy is still out lost on the island, persuades Jerry to find him. Jerry, accompanied by Dodge and Cobb, head out to the abandoned barn and find the dogs running away. Dodge, armed with a rifle, shoots and kills a dalmatian as the pack runs off. Inside the barn, the men find Lois' mangled body lying in a corner, but do not find Tommy.
Dodge, believing that his son is dead, steals Jerry's jeep and drives off in pursuit of the dogs, with Jerry and Cobb following him in Cobb's truck. Dodge soon encounters the pack near one of the abandoned houses, but before he can even shoot at them, the dogs attack him and tear him to shreds. Jerry and Cobb soon find Dodge and drive off the dogs with their truck, but Dodge succumbs to his injuries and dies the next day. After failing to send a signal out to the Coast Guard on the radio, Jerry orders Millie, Walter, and Cobb to find whatever weapons they can use against the pack, but the only weapons they can find are Jerry's shotgun and a handful of cartridges, a couple of sticks, an umbrella, and a few knives.
Later that same day, Jerry, his family, and the few remaining inhabitants find themselves under siege by the pack. Later that afternoon, the mongrel and four other dogs from the pack launch an attack on the house, trying to break in through the windows. Jerry, Millie, their sons, and Cobb struggle to hold them off. Two of the dogs, a Doberman Pinscher and an Irish setter, manage to break inside the house, but Jerry kills the setter with his shotgun and Walter and Jerry's dog Riley drive the Doberman out of the house. The rest of the dogs flee after failing to break through the windows.
Realizing that the dogs will return for another assault, Jerry tells his family, Marge, Cobb, and Walter to board up the windows and doors of the house. Later that night, the group carries Dodge's body down to the docks and place him in a boat, pushing it out to sea to prevent the pack from trying to get at it. Knowing that the dogs will be back, they then quickly return to the house and lock themselves inside.
The following morning, Walter wakes up and hears the sound of a motorboat near the docks. He grabs Jerry's shotgun and runs down to the docks to find a small group of people in a motorboat several yards out at sea. He fires a shot in the air, trying to signal them to land at the docks, but the people believe he is threatening them and drive away. Walter turns around, only to find the dogs standing in his way. He fights them off with the gun, but the mongrel and two other dogs quickly overpower him and knock him off the deck into the water.
Meanwhile, Jerry, having heard the sound of the shotgun being fired and realizing that Walter has headed down to the docks, takes his jeep and drives down there, only to find him surrounded by the pack. As Jerry drives his vehicle onto the dock, the dogs turn their attention towards Jerry and charge him. The moving jeep runs over the majority of the pack, killing a gray terrier mongrel and forcing the rest of the dogs to retreat into the forest. Jerry pulls Walter out of the water and drives him back to the house.
Tired of waiting for help, Jerry orders Millie to take Marge, Riley, Walter, and their sons out to the docks, while he and Cobb would try to finish off the pack. While Cobb waits quietly in Jerry's jeep, Jerry lures the mongrel and the remainder of his pack into the house. As soon as the dogs are all inside, Cobb closes the door behind them, pours several bucket-loads of gasoline on the walls, and sets the house on fire with a torch. Jerry then climbs up the ladder to the attic and tries to raise it to prevent the dogs from following him, but the mongrel leaps on top of the ladder and manages to reach the top. Jerry holds him off for a short while, but as the flames reach the floor of the attic, he pushes the dog back and jumps through a window, sliding off the roof and lands on the grass below. The mongrel leaps out of the same window and springs at Jerry, but he misses his aim and is embedded on the sharpened end of a broken pipe.
Millie and the others return to the house and watch as the burning building explodes and collapses, killing all the dogs inside. They soon discover that one of the dogs, the same dog that was abandoned and had joined the pack a few days earlier, had apparently did not join the fate of his comrades because the rope he was tied to had been caught and tangled in a heavy branch. Realizing that the dog was apparently afraid and not as savage and aggressive as the other dogs, Jerry decides to try to tame it. Using some crackers, he feeds them one by one to the dog. The film ends as the dog starts licking Jerry's hand, apparently winning the trust of the man and becoming a pet again.
|Complete credited cast:|
|||Joe Don Baker||Jerry|
|||Richard B. Shull||Hardiman|
|||Delos V. Smith Jr.||McMinnimee|
|||Richard O'Brien||Jim Dodge|
|||Paul Willson||Tommy Dodge|