Penny and Louise may not be enlisting, but they do their part for World War II by working to foil some saboteurs bent on hindering the US's war effort in Riverview. The first attack comes in the very first chapter. The girls are witnesses because Pop's Worry, Mr. Parker's sailboat, overturns while Penny is trying to grab a bottle with a message in it.

Suspicion for the attack falls on a local young man who doesn't make things any easier on himself by being so angry over his arrest that he refuses to cooperate. Luckily for his and his sister's business, the sister has more sense.

Jerry Livingstone, ace reporter for Mr. Parker's paper, the Riverview Star, is training to join Uncle Sam's Air Corps [Air Service to Army Air Corps to Army Air Forces to Air Force], but he's training locally, so he's still around. Ms. Wirt has Penny note that familiar faces have been disappearing from the paper, but Jerry will be a special loss. (By the way, in chapter six Jerry calls Penny 'Miss Pop-Eye' for her love of sailing.)

A subplot regards a man nicknamed 'Old Noah' who has built himself an ark and filled it with animals. (Had to chuckle when he explains to Penny and Louise why it's not made of gopher wood.) Louise is afraid of the old man, but Penny thinks he's darling. The sheriff does not agree.

There's a night club or cafe that may or may not be a meeting place for the saboteurs to investigate. I'm afraid I can't share Jerry and the girls' consternation when they learn that almost nothing on the menu is under a dollar. They try to eat cheaply, but the cover charge, sales tax, and tip bring the total to more money than they have with them. Will they have to wash dishes to make up the difference?

If the saboteurs' first effort hadn't been bad enough, they've got a bigger _target in mind. Can our girls get themselves free in time to prevent disaster? What about the Sheriff and Old Noah?

It's an exiciting adventure on land and water. Nice that the war wasn't ignored. Also nice that Louise's father has a minor role. It'd been so long since I read this series that I wasn't sure that Mrs. Sidell wasn't a widow.

Why is Penny's nose described as freckled in chapter one and her golden hair as auburn in chapter three? Trouble from the Stratemeyer Syndicate over Penny's obvious physical resemblance to Nancy Drew? Her hair looks almost as dark as Louise's in the frontispiece. ( )