A stocky, red haired middle aged woman, Irma Bunt resides at the mountain-top clinic of Piz Gloria with Ernst Stavro Blofeld. Bunt is first introduced at a train station taking Bond up to the clinic by sleigh and helicopter while he is disguised as Sir Hilary Bray. She ostensibly looks after the girls who are suffering allergies – and secretly being brainwashed into "angels of death" — and has dinner with them and "Sir Hilary". A red-haired disciplinarian in the mold of Rosa Klebb, Bunt is determined to keep any fraternizing between "Sir Hilary" and the girls kept to a minimum. In the film Bond himself subtly insults her by telling her that her name comes from a nautical word for the baggy, swollen part of a sail, though in the novel Bond starts tricking her into thinking she's a duchess.
When Bond escapes from Piz Gloria after his cover as Sir Hilary Bray is blown, Bunt helps some of the men pursue him in the village at the bottom of the mountain with a Mercedes-Benz W111. She fails in this and is almost killed when she is caught in an explosion at a stock car rally which Tracy had led her into in an attempt to shake her off. Bunt and the other three occupants of the car managed to escape it just before the explosion, but one of them was caught in the blast while crawling away.
She is not seen again until right at the end of the film after 007's wedding. Bunt shows up, alive and well, in a car driven by Blofeld. As they pass the newlyweds, Bunt leans out of the window and fires at Bond with an M16. Bond is unharmed, but Tracy is killed. It should be noted that although Blofeld was merely the driver in this drive by shooting, it was Irma Brunt who had the machine gun and opened fire. Bond however held Blofeld responsible.