The Question and Answer section for The Open Window is a great resource to ask questions, find answers, and discuss the novel.
Framton suffers from a nervous condition and isn't terribly social. He is in the country for a rest cure, and he is only visiting because his sister insisted on giving him a list of people to call upon.
Vera wants to scare Mr. Nuttel with a tall tale about her family history. She needs to make sure Mr. Nuttel does not have any background about her family.
Vera knows why Framton is there. She knows that Framton is nervous and she easily sucks him into her tall tale.