Ava Gardner plays Scott 's mistress in the film Seven Days in May .
Other than the billing , `` Also starring Ava Gardner as Eleanor Holbrook '' ( Scott 's mistress ) , none of the other characters are identified by name in the credits , thus although Kirk Douglas ' `` Jiggs Casey '' and Andrew Duggan 's `` Mutt Henderson '' are described in the book as having the given names of `` Martin '' and `` William '' , respectively , those names are never mentioned in the film .
Seven Days in May