“Toni Erdmann,” a nearly three-hour German picture about the strange relationship between a daughter, her estranged father and his alter ego, sounds like the stuff of a Bergman drama or some other psychoanalytic endeavor.

In fact, it’s anything but that. Under the skillful eye of director Maren Ade, the movie is certainly unafraid of embracing the weird, but it is an inherently sweet and oftentimes moving picture about the lengths to which a parent can go to help a child in distress.

Peter Simonischek is Winfried Conradi, who surprises his workaholic daughter Ines (Sandra Hüller) at her job working as a consultant for a Romanian oil company.

He sticks around for awhile and then returns in the guise of a motivational speaker named Toni Erdmann, sporting a pair of ridiculous fake teeth and a commitment to understanding and helping his daughter as he couldn’t while being himself.

The movie defies easy characterization — there are scenes defined by silent tension between father and daughter, and others that revolve around droll comedy. There’s a surreal sensibility underpinning it all that’s simultaneously grounded in reality.

This is challenging terrain and it depends heavily on compelling and multi-layered performances to go along with a precise filmmaking touch.

In that area, Simonischek succeeds but this is really Hüller’s movie. Her Ines is one of the most fully realized movie characters to come around in a long time. She turns rigidity into an art, shading it at different times with practically every emotion a human can feel and presenting an overarching picture of a woman struggling to face the professional and personal pressures that most anyone watching the picture will recognize.

She’s the key element that balances the movie and keeps it compelling during the inevitable slow patches given the expansive running time.

It’s important to maintain the authenticity that she brings, which keeps the movie from tipping over into out-and-out satire and underlines the key point that seems to be the essence of “Toni Erdmann,” which is that life is strange and lonely and difficult, but also warm and comforting, often simultaneously.

The notion is best illustrated in one of the movie’s showcase scenes, in which for reasons that won’t be explained here, Ines belts out a full-throttle, impassioned version of Whitney Houston’s “The Greatest Love of All.” Ade keeps the camera glued to her star for virtually the entire song, and a lifetime of experiences appears to rush over her during those few minutes.

That’s as apt a summation of modern life as any.