It's difficult enough to make a good play work on the screen. Presumably, a filmed adaptation of a play in which the main character spends most of her stage time dying in a hospital bed would have an especially rough time of it. Nevertheless, director Mike Nichols, working from a script co-written with star Emma Thompson, does just fine by Margaret Edson's Pulitzer-winning off-Broadway play Wit. Playing an authority on the poetry of John Donne, Thompson becomes a subject of analysis when a diagnosis of late-stage ovarian cancer whisks her into an aggressive, experimental regimen of chemotherapy. Instead of studying the elevation of the soul through God, Thompson is forced to contemplate the degradation of the body through biology. Speaking to the camera, she faces the task with the same unsparing, acerbic observational skills that made her both feared and loved in her field, only eventually beginning to question how appropriate her skills are to her situation. As a director, Nichols doesn't add much to the source material, but his few additions become significant, as he uses flashbacks to bend time and help translate Edson's postmodern touches. But mostly, he keeps the performances in sharp focus and lets his actors do the work. In her role as a woman who attempts to mock her situation even as it overpowers her, Thompson delivers a twisty, powerful performance, maintaining her dignity while delivering clever observations punctuated by violent bouts of nausea. Given the powerful work of its star, the film's ability to survive its trickiest move proves its strength: Its third act is carried almost entirely by a supporting cast of relative screen newcomers, including stage veteran Audra McDonald as Thompson's nurse and Jonathan M. Woodward as a doctor who once took her notoriously difficult class as a personal challenge. Each contributes to a subtle, creeping emotional tone that never feels cheap. Ultimately, Wit feels like a meditation on final matters that Donne, no stranger to the pairing of tortuous cleverness and matters of the utmost gravity, might recognize as a descendant of his work.