Wanted - 7 Fearless Engineers!

A great civilization's fate lay in Dick Barrow's hands as he led his courageous fellow engineers into a strange and unknown land. None of them knew what lay ahead--what dangers awaited them--or what rewards. But they did not hesitate because the first question asked them had been: "Are you a brave man?" (Summary from jacket blurb/intro) Written by F. Orlin Tremaine using the pseudonym, Warner Van Lorne.