Ben Redding has been sent ahead of the herd traveling up the Chisholm Trail through Indian Territory. The herd needs water in the worst way, and a drought has dried up most of the creeks and turned rivers into streaks of mud. When Ben finds a clear, cold pool of water on the prairie, he thinks he's found an oasis, until he discovers what lives in the water, and what her price is for a drink. Can he return to the herd in time to warn them? Will thirsty cowboys even believe what he saw?