When several townspeople come down with mercury poisoning, Dr. Mike forces a reluctant Sully to guide her to the high mountain stream which may be the source of the problem. The trek is difficult for her, but she ultimately earns Sully’s respect and gratitude after saving his life twice despite a broken wrist. Just as they confirm that the water is being polluted by a local mine owner whose mining process is dumping mercury into the stream, they are captured by his men. In the interim, worried townsfolk send out an inept posse to try to locate Sully and Dr. Mike. Olive backs Grace’s new venture — Grace’s Cafe. In the end, Dr. Mike saves the day by curing the mine owner’s son, who has fallen victim to the poisoned water, and convincing the owner to close the mine.