I don’t even know what else to say about it.
So, there’s this girl, Elsie. The letters of the title are her diary, and she’s super obnoxious and she’s got a car. Everything’s kind of coy in that way where the author uses a first-person narrator’s apparent innocence to reveal all their terrible character traits and it’s supposed to be cute. Think The Letters of her Mother to Elizabeth.
Elsie’s father, besides living off the income he married Elsie’s mother for, is a sort of inventor, and the book takes a weird turn into the vaguely sci-fi when he invents an airship and they fly to Europe in it. But it’s all pretty sketchy by that point, because Elsie’s father has picked up a newsboy from New York to adopt or educate or something, and from that point on, most of Elsie’s diary is retellings of his stories, complete with slang and phonetic spelling of his terrible accent.
Seriously, it’s so, so bad.