One of the masterstrokes of Sarah Gubbins’s screenplay is how deftly she underscores the differences in the perception and presentation of the sicknesses within this marriage.

Gubbins’ script is tart, verbally lively and neatly constructed, while director Josephine Decker, in her first outing since her well-received 2018 Sundance entry Madeline’s Madeline, keeps a very tight rein on things, adroitly mixing in tension, innuendo and dark humor to keep the drama at a satisfying low boil most of the way.

This is a fictional biography, and yet every moment rings true.

Decker is a superbly imaginative director, which leaves one wishing her creative powers had pushed the film even further away from the constraints of reality. But that’s a downside that comes with working from material written by another artist.

Decker’s characteristically sawtoothed and delirious new film is set in the same latent space between fact and fantasy — a story and its telling — where she located all of her previous work.