This is a children’s novel about an orphan girl who is raised by her grandparents, until circumstances force her to live with her cousins and aunts. There she plays a secretive game, where the children fetch magical objects from mythical worlds.
Reading this, you can easily see why Diana Wynne Jones was friends with Neil Gaiman. The novel makes a number of literary allusions, but main ones are to Roman gods. Roman gods are a bit of an odd choice, because everyone’s accepted that Greek culture is just classier, but it fits well with an astrological theme. The whole thing reminded me of Eight Days of Luke.
It’s a short book, and given how much I enjoyed it, I think it was worth the effort.