Sent to study claims of ecological contamination, a cynical doctor and his pregnant wife (Robert Foxworth and Talia Shire) not only encounter disastrous and deadly effects to surrounding wildlife and the Native American tribe inhabiting the area, but a towering mutation in the form of a crazed and deformed bear. Its take on environmental issues is one rarely seen in horror cinema. Compared to most similar films which use nuclear waste as a device to simply create monsters, it is intelligently written with sound cause-and-effect. At the same time, I found the scientific weight fascinating as well as frightening. Writer David Seltzer deftly based the script on the tragic story of Minamata, Japan. The mutation's onslaught in the third act is poorly handled with choppy and evasive editing revealing sfx limitations. Yet despite this, the suspense holds up pretty well until the conclusion. But unreconciled plot points left me somewhat disappointed.