When an actor steps onto the set with no lines and no script, magic or disaster may ensue. In the 2021 mystery thriller film My Son, that actor is James McAvoy — and the absence of a safety net is the point. During the rigorous filmmaking process, director Christian Carion supplied only a character sketch and a scene objective, leaving McAvoy to invent his responses in the moment as a father searching for his missing child. Prewritten dialogue was tossed out, so every reaction lands unplanned and immediate.
While Carion, Claire Foy, and the crew worked from a prepared storyline, McAvoy entered each scene blind. He discovers the mystery in real time, asking questions and absorbing answers as they arrive. The gamble could have collapsed into chaos; instead, it builds a crackling tension born of first takes. The camera watches a man come apart in front of it, turning the search into something bracingly authentic. Explore the intricacies of this groundbreaking performance below.
James McAvoy’s Improvised Masterclass in Fear
Improv is usually left to comedy, yet in My Son, it gave James McAvoy one of the rawest performances of his career. From the opening moments — Edmond standing at a taped-off crime scene, fumbling through questions from police and hugging his ex-wife Joan —the tension plays out in real time. The camera lingers on his listening face as he waits for clues, not knowing what will be revealed next. That uncertainty carries through the film, making every stumble, flare of anger, or moment of grief feel discovered rather than performed.
Where characters like Liam Neeson’s Bryan Mills in Taken are always two steps ahead with their pre-planned moves, Edmond is a man constantly playing catch-up. The unscripted approach strips away the usual gloss of a heroic protagonist. McAvoy’s performance leans on hesitation, missteps, and startled reactions, with his character grasping for answers instead of providing them. That rawness turns the story from a simple mystery to solve into a tense, drawn-out ordeal experience where each revelation feels earned.
McAvoy later admitted in an appearance on The Graham Norton Show that working without a script sometimes led him to make unusual choices. In one instance, startled by a car during a take, he scrambled up a tree to hide. He figured it was a clever instinct until Carion bluntly told him it wouldn’t work. That moment shows the balance of the whole film: improvisation made McAvoy’s acting exciting, but it also meant he could make choices that didn’t fit the story. As he works through the mystery in real time, he learns things at the same time as his character and audience, and that sense of shared discovery gives the film its energy.
Christian Carion’s Risky But Brilliant Experiment
Although it screams innovative, McAvoy is not the first actor to nail this brave performance. Carion had already tested this method in Mon garçon (2017), the French original of My Son. In that film, Guillaume Canet also improvised the role of a desperate father while the rest of the cast followed a prepared script. Knowing it worked before likely gave Carion confidence to try it again in a new language and setting.
Because the premise is so simple — a father trying to find his missing child — there’s room for uncertainty. Carion used the remake to push that uncertainty further, letting McAvoy react not only to plot turns but to the environment, the actors around him, and the surprises that arose during filming. That echo of the French version gives My Son its roots, but the risks in the remake sharpen the effect: every moment feels like a choice made in the shadows.
Carion’s role shifted from a traditional director to more of an architect of chaos. He set the conditions for reality to happen, then let the cameras roll. The suspense in My Son comes from the simple, terrifying feeling that literally anything could happen next because the main character truly doesn’t know what he’s doing. Carion’s brilliance was in understanding the power of the fear of the unknown, and he found a way to make that feeling authentic for everyone involved. By abandoning the traditional approach, he and McAvoy crafted a unique, immersive viewer experience that leaves a haunting impression, blurring the line between observer and participant in an unfolding tragedy.
For a chance to witness McAvoy’s raw, unscripted performance, My Son is now streaming on Prime Video.
