Experimenter is based on the true story of famed social psychologist Stanley Milgram, who in 1961 conducted a series of radical behavior experiments that tested ordinary humans willingness to obey by using electric shock. We follow Milgram, from meeting his wife Sasha through his controversial experiments that sparked public outcry.

The strained relationship of an engaged Brooklyn couple, Theo (Chris Messina) and Nat (Rashida Jones). Theo is bored with his job as a wedding photographer-the generic backgrounds, the artificial posing, the stilted newlyweds-so he develops an unconventional side business, called "Gumshoot," a service where clients hire him to stalk them with his camera. Becoming infatuated with one of his clients, a mystery woman who goes by the name Subgirl (Meital Dohan), Theo develops a voyeuristic obsession that forces him to confront uncomfortable truths about himself and his impending marriage.

The story of William Vincent as he recounts the eccentric and curious path that has brought him, at mortal risk, to New York City, after four years in exile, to rescue a woman he scarcely knows, Ann, from the vague crime syndicate that first brought them together.