Wings of the Storm.

A dog named Thunder, the weakling of his brood, is born in a lumber camp in the North Woods, operated by Anita Baker. The cowardly dog is cast out of the camp and adopted by forest ranger Allen Gregory. Meanwhile, Bill Martin, the brutal camp superintendent, covets both Anita and her property. When Bill attacks Anita, Thunder comes to the rescue and proves his courage by warding off the villain.