Tony is pretty much an everyman
character going about his daily business when he happens to see what he sees, which leads to one of Argento's more memorable set pieces as Tony is
trapped between the two glass doors of the art gallery, unable to help the victim inside who is bleeding on the floor and unable to escape outside to fetch help, and his and Julia's situation and relationship is played out in a very natural way, the scenes in their apartment with just the two of them interacting being as integral to the plot as the more
violent scenes.