In this sequel to And Then Everything Unraveled, Delia has started the search for her mother. This quickly leads to complications: the clairvoyant Caroline is still giving cryptic advice, the artiste Dieter has decided that the best way to help Delia and her aunt keep a low profile is to paste up pictures of them everywhere, Quinn (who may or may not be her boyfriend) is grounded for being involved in an underage betting ring, and people (including Quinn's father) appear to be trying to kill Delia. Everything keeps leading to Buenos Aires, so that is where Delia eventually ends up.
One should not take a book like this too seriously. It's the sort of adventure where a breathless chase scene is interrupted with less-than-subtle references to brand-name shoes and a heated discussion about saving people's lives is on equal par with angsting over whether Quinn really likes Delia or not. In sum, a mystery of international intrigue and deceit that could lead the cataclysmic environmental change and the romantic mysteries of teen boys are of similar significance. So, it's all in good fun. Those looking for redeeming educational value can take some heart from the cultural tour of Argentina, but none of that is really the point.