Hardy-guttene og strålepistolmysteriet

Blurb

The Disappearing Floor is Volume 19 in the original The Hardy Boys Mystery Stories published by Grosset & Dunlap.
This book was written for the Stratemeyer Syndicate by John Button in 1940. Between 1959 and 1973 the first 38 volumes of this series were systematically revised as part of a project directed by Harriet Adams, Edward Stratemeyer's daughter. The original version of this book was rewritten in 1964 by James D. Lawrence resulting in two different stories with the same title.
UK version published by William Collins Sons & Co. Ltd. as The Mystery of the Disappearing Floor, Volume 5, in 1971.