Through sun and storm, loves entwine on a blossoming family vine

With “Three of Hearts: A Postmodern Family,” documentarian Susan Kaplan has achieved the enviable effect of eavesdropping on her subjects -- three individuals living without conventional boundaries -- for a meaningful exploration of the possibilities and the limits within any relationship.

Sam Cagnina and Steven Margolin, with whom Kaplan discovered she had been acquainted separately, lived together for seven years before forming a menage a trois with Samantha Singh. The trust Kaplan inspired in these three people, along with their families and friends, made possible a crucial sense of intimacy in telling their story as it unfolded over eight years.

As the movie opens Samantha discovers that she is pregnant, a joyous occasion but more momentous than any of them realize. Sam and Steve met and fell in love in college and settled in Manhattan. Both had from time to time been attracted to and involved with women, and at one point Sam suggested that bringing a woman into their relationship would enrich it, and Steven agreed. Eventually Sam met Samantha, a Toronto native of East Indian ancestry and a struggling actress.

By the time Samantha becomes pregnant, she, Sam and Steven have been living and working together for nine years. They have become proprietors of the Ananda Wellness Center, where Steven worked as a chiropractor, Sam as a massage therapist and Samantha as office manager. But the birth of their daughter, Siena (the identity of the biological father was initially considered unimportant), followed by the birth of a son, plus Steven’s insistence that they move the business, now called Dr. Margolin’s Wellness Center, into different quarters put strains on their relationship that none of them apparently anticipated.

Samantha is a stunningly beautiful woman with a strong, confident presence. Sam and Steven are good-looking men, and while Sam is short, stocky and outgoing, Steven is tall and reserved. Their families are largely accepting of their arrangement, although in Toronto Samantha’s more conservative family passes off Steven as Sam’s cousin.

As hard as it is on the three, the increasing stress on Samantha, Sam and Steven is pure gold for a documentarian. What the three discover is that over their 13 years together they had put so much into making their unusual situation work personally and professionally that they had given little thought to their needs as individuals. This awakening creates a series of formidable challenges, but what Kaplan discovers is that three people who had the courage to defy convention and fashion a unique lifestyle for themselves also had the strength to confront head on anything that life dealt them while remaining united in their desire to do what was best for their children. “Three of Hearts” is above all a portrait of three people committed to living their lives to the fullest, no matter what.

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‘Three of Hearts’

MPAA rating: Unrated

Times guidelines: Complex adult themes

A ThinkFilm presentation. Director-producer Susan Kaplan. Producer Sarie Horowitz. Principal cinematographer Sarah Cawley. Editor/associate director Toby Shimin. Music Ross Levinson. Featuring songs by Catie Curtis. Running time: 1 hour, 37 minutes.

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