Sanjayan explores humankind's relationship with the Earth's most important resource: water. Unraveling dramatic connections between fresh water and the health of the planet, he uncovers spectacular wildlife stories that center on managing the natural pulse of the planet's water. The episode includes a kayak journey that follows the Colorado River to the sea; the elephants and people at the singing wells of Kenya; the surprising connection between AIDS and a small fish in Lake Malawi; and a look at how hunters in America saved one of the greatest gatherings of birds on the continent.