Two character plays—known in the biz as two-handers—are always a challenge: for the actors, certainly, but also for the audience. No matter how charismatic the performers, these must be fascinating characters telling a continuously compelling story to hold our interest. Michelle Williams and Jeff Daniels are the latest to take on the assignment, co-starring in a revival of David Harrower’s “Blackbird.” at the Belasco Theater.

I could go for a really lame pun here—the play could hardly be “harrower” – but the subject of this laugh-free drama is, after all, child sexual abuse. Is it always as simple as it first appears? While we may think we know exactly why these two people have ended up together ten minutes into the action, the script–aided by director Joe Mantello’s fine direction– keeps us guessing and switching allegiances right up to the end.

As to where the fireworks begin, the play opens smack in the middle of the couples’ first encounter in fifteen years. Williams’ now 20-something Una confronts the 50-something Ray (who has taken on a new name) in his workplace. Since she was only twelve when their illicit affair occurred, the experience landed him in jail for a few years. But as we soon realize, it is Una who may have actually done the most emotional time.

She has shown up all these years later clearly seeking something, be it revenge or apology. This is a bruised and broken young woman still tender at the bone, as much as for how he ended the relationship as for why he started it. (“I was left alone…and I was left in love.”) Theirs is a hazardous memory lane, veering from anger to regret to tenderness to, yes, momentarily renewed passion. There is a surprise ending about which we dare not speak. Suffice to say, audience members leave the theatre with ambiguous and widely varying interpretations.

About those audiences, be warned: this is hardly your mother’s matinee. There is frank sexual talk that probably shocked a lot more when the play first emerged in 2007. Now it’s almost ho-hum compared to what we see on cable, and even just a tiny bit embarrassing coming from the two actors. It is this bold-faced pair who are bringing in star struck ticket buyers and famous folks alike. (Chris Rock was in my row)

While I confess that there were a few moments I felt I could be sitting in a Stella Adler workshop, Jeff Daniels and Michelle Williams are mostly up to the task. Ray is so discombobulated when the play begins–Daniels pacing like a caged lion—it seems he has nowhere to go. Fortunately, the actor hits most the notes once he calms down. There may be some who would wish for a slightly more traditionally virile and irresistible actor in the role. I second that emotion.

Williams has the more difficult role and while there are some detractors, I think she disappears believably into this wounded young woman. Her physicality works beautifully, making the most of taking off a down jacket or letting her limbs tell stories of their own. The actors’ constantly shifting emotions and motives are a challenge for them and for us, and by in large, it works.

If anything, I wish their material was more dazzling. I kept wondering what (here I go again) David Hare would have brought to it. Just a bit more complexity, a tad more wit, I imagine. Scott Pask’s set is a cleverly designed corporate ‘everyoffice’—into which Una has caused the most non-ordinary disruption. While not much here to “enjoy,” there is much to chew on. First and foremost, how one can’t ever leave the past entirely behind.