This schlock horror classic from the 1970s is a product of the career ebb experienced by director John Frankenheimer. Robert Foxworth stars as Dr. Robert Verne, an inner-city physician renowned for his compassion and fairness. So he's asked by the EPA to mediate a dispute between Native American tribes and a polluting paper mill in isolated northern Maine. Accompanied by his pregnant wife Maggie (Talia Shire), a classical musician, Robert journeys to the deep woods, where he meets the tribal leader, John Hawks (Armand Assante) and a representative of the mill, Mr. Isley (Richard Dysart). It turns out that the mill is indeed poisoning the local water supply with mercury, causing illness among tribe members and some mutated local wildlife. The Native Americans and the paper mill point fingers at each other for a rash of recent disappearances in the area, but Robert believes that something more ominous is responsible when he observes a huge salmon eat a duck. He's proved right when he encounters an enormous, mutated grizzly bear with a taste for human flesh. Unfortunately for Robert and Maggie, he has taken one of the creature's cubs back to camp, leading an angry mother bear to his tent flap.
~ Karl Williams, All Movie Guide