Tilda Swinton reckons the scariest thing about filming her latest movei was being pelted with rotten tomatoes in an unruly mob.
The actress plumbs the depths of grief and despair for her role as a mother whose 15-year-old son commits a school massacre in We Need to Talk About Kevin.
The film's arresting opening scene shows Tilda's character, a travel writer, in a sea of red goo and writhing bodies at the Tomatina festival in Spain. Director Lynne Ramsay had the star plunge into the melee, in which tens of thousands converge on the town of Bunol for a messy food fight.
The scene is vivid, exhilarating, overwhelming and frightening - rather like the film's depiction of parenthood.
"It was really, really intense," Tilda said at the Cannes Film Festival, where the movie is an early favourite to take prizes. "It's not the kind of thing where you can say, 'We have to do it again'.
"Every time I see the images I can smell the mixture, not only rancid tomatoes and beer - but testosterone. It's just testosterone.
"The film was always going to be incomplete until we had that testosterone in it," she said.
While critics have praised Kevin, its depiction of motherhood made some viewers uncomfortable. Tilda, 50, says the film hits a nerve because it tackles a taboo - the admission that child-rearing is a rough business.
"I remember very soon after giving birth realising that my imagination had taken on a kind of brutal capacity that it had never had before," said the actress, the mother of teenage twins. "Pregnancy is brutal as it is, but there is something about the experience of childbirth that stretches in every sense your imaginary capacity for brutality."