While seeking to solve the mystery of ” the trained vampire murders,” Doc Savage and his amazing crew suddenly find themselves prisoners of Sol Yuttal and Hadi-Mot aboard a hijacked Zeppelin. Their deadly destination is a fabulous lost diamond mine guarded by carnivorous plants and monstrous, bloodsucking bats.
James Nobel has suggested the Bantam artist for The Lost Oasis is Stanley Meltzoff based on a signature seen only on the first French edition of the novel.
From the Meltzoff website:
Scan of sig from personal copy: