Harriet Pyne Grove. 1930.
This is a literally descriptive title: the mystery is S.P. -- no one knows what it means, especially the group of girls who give their new club the letters for a name. They start the club partly because the boys have one, and partly because there are no youth organizations in their small town. While they decorate their club room, entertain their friends to dinner, and talk the new high school science teacher into taking them on bird walks -- and while they plot and plan to go camping in the summer -- they try to think up acceptable meanings for their club name. They have lots of help, facetious and otherwise, from their fathers and from the boys.
Exactly halfway through the book, though, the reader (if not the characters) is allowed to start another mystery. Greta Klein, unlike the rest of her dysfunctional family, speaks English better than German. And, unlike almost anyone, her memory only goes four years back.
When Greta eventually meets the S.P.s -- three quarters of the way into the book -- her mystery gets cleared up in a hurry, due mostly to chance.
Good dialog, believable characters who develop in the course of the action, and a nearly-believable plot (I've certainly run into less credible stories than Greta's, although I can't off-hand say where) make this a better book than many other Grove titles I've read.
© 1995 Jo Anne Fatherly
(This review first appeared in The Whispered Watchword, the newsletter of The Phantom Friends)