Except for a totally extraneous last chapter, this was a solid "cozy" mystery focused on Beverly's undercover assignment to keep an eye on a suspicious scientist. Since World War II was mentioned in an earlier book, when Terry joined the English military to fight for his country, it's odd that no specific mention is made of the U.S. being at war in this one, which was published in 1944, but that may have been a publisher's decision. I expect readers at the time read between the lines. Otherwise, having Larry fly off to England to work on the plans for a new plane would also have seemed a bit strange. Most of the young men the girls are dating or engaged to would have enlisted by now if the story line had tried to be completely realistic. Read today, it actually holds up pretty well.