Sam, a neurodivergent man, has a daughter with a homeless woman who abandons them when they leave the hospital, leaving Sam to raise Lucy on his own. But as Lucy grows up, Sam's limitations as a parent start to become a problem and the authorities take her away. Sam convinces high-priced lawyer Rita to take his case pro bono and in turn teaches her the value of love and family.

A philosophical burlesque, Human Nature follows the ups and downs of an obsessive scientist, a female naturalist, and the man they discover, born and raised in the wild. As scientist Nathan trains the wild man, Puff, in the ways of the world - starting with table manners - Nathan's lover Lila fights to preserve the man's simian past, which represents a freedom enviable to most.