This is a disturbing but compelling book about a pair of whimsical and unformed twins who get caught up in a cult-like movement and the personalities who engendered it. The story is told from the point of view of one of the twins, Harriet, who has never made a decision for herself, forestalling judgment and common sense to follow the wishes of her twin brother whom she adores. The book is frustrating because Harriet has so many chances to break out of the movement and she recognizes all these opportunities. But she stays within it even when she doesn't actually believe it. (She stays first because her brother tells her to and then later because she loses herself in one of the movement's key directors and cannot do without him. This in itself is terribly irritating because it's not made clear why she tethers herself to him when he is so superficially interested in her).

I call the twins 'unformed' because it appears that although they have a lot of feeling, they do not appear to be fully developed. They are like embryos when it comes to having personality and strength of will, unable (it seems) to think for themselves, deferring to the other twin. And throughout it's clear that two unformed personality-less characters do not make a whole person.