Image by/from True Williams
The Key Panel is Volume 25 within the original The Sturdy Boys Mystery Tales printed by Grosset & Dunlap.
This book was written for that Stratemeyer Syndicate by Harriet S. Adams in 1946. Between 1959 and 1973 the very first 38 volumes of the series were systematically revised included in a task directed by Harriet Adams, Edward Stratemeyer’s daughter. The initial form of this book was shortened in 1969 by Priscilla Baker-Carr leading to two slightly different tales discussing exactly the same title.
Innocently answering a motorist’s ask that they turn off an easy at his home, the Sturdy Boys uncover an in-depth mystery: the person used the a guy, John Mead, that Chief Collig claims died 5 years earlier inside a vehicle accident. Contributing to the mystery, the Mead mansion’s doorways have neither knobs nor visible keyholes. Once talking with a locksmith professional will they discover the locks were hidden.
Meanwhile, their father Fenton assigns these to investigate a lead within the kidnapping of the physician that could lead lower the path to some local boy who fell along with a nearby crook, an expert criminal, who’s a regards to the boy. The Sturdy boys are to discover a traffic signal that hums like someone singing faintly, and drive 10 mins from this in every direction, then investigate position for a “secret panel”.
Fenton’s mystery winds up intertwining using the Mead mansion and also the master criminal, who’s been transporting out a number of break-ins and thefts without triggering the security systems. Apparently , the deceased Mr. Mead was an electronics genius who created a device that may open any lock and defeat security systems, but requested that, upon his dying, it’s switched to the FBI. The actual criminal had befriended Mr. Mead, discovered the unit, and stolen it.