Ace 1964 paperback (F-297.) Cover by Ed Emshwiller, 156 pages. Condition is only Good+: tight with 1/8" tilt; spine is flat or very slightly dished with a line down length and some edgewear; age-tanning is mild to moderate and uniform (consistent with age); insides of covers are darker. Moderate wear to front cover including several finger-creases towards bottom/middle; back cover has less wear but has a few faint lines at bottom/middle. "ChUSFA" stamps on first page and page 85 - no other marks or writing.

Henry Kuttner's Valley of the Flame, in its first book appearance. The magazine version appeared in Startling Stories March 1946 as by "Keith Hammond." Most sources consider C. L. Moore to be co-author on this. Since their marriage in 1940, almost anything they wrote had some element of collaboration, particularly when using pseudonyms... the style and type of story fit, too. It's been decades since I read this story - I'll have to quote from the back cover:

Deep in an unexplored jungle, Brian Raft sought the secret of the legendary VALLEY OF THE FLAME. Somewhere there was a radioactive fire that could perform miracles of super-science. Somewhere there was a place where cat-people prowled, where time was altered, and incredible mysteries held their secrets of power and fortune for the daring discoverer...