From what I hear she pursued it in all directions.

Strangers on a Train (1951)

Chosen by Emma Jones who had this to say: 'Strangers on a Train ended up being one of the last Hitchcock films I saw. This was mainly due to the fact it is hardly shown on TV and this was a time when buying videos of films was both rare and expensive. I would pan through the films section of the Radio Times every week in the hope of catching a Hitchcock film to add to my recorded collection. I was in the end rewarded for my patience and collected my gem on an obscure week night (paranoid that my Dad had set the video wrong I sneaked downstairs to check the player was whirring and had the red record button lit). I thoroughly enjoyed the film, made even sweeter by the wait. It is a truly original thriller, with a story line that has been copied in films and even sitcoms. Farley Granger hardly made any films due to his untimely death and his two Hitchcock outings (Rope being his other) are by far his best. There are no weak links in the casting and a gripping scene that makes you think twice about going on a carousel!'

Massively influential (filmaday has already covered one film out this year based on this premise) but still gripping and tense.
Hitchcock is clearly a master at these games, there are many iconic images (Bruno staring ahead as everyone else looks side to side at a tennis match is a simple but unsettling image) amidst the silliness nessecary to ratchett up the tension (oh he just happens to drop the all important lighter down a drain - how convenient!).
Patricia Hitchcock is delightful as the younger daughter of a senator who seems pretty keyed in to the reality of the situation.