Adventure At Black Rock Cave by Patricia Lauber, Scholastic paperback printing, TW286, 1964, 63 pages. Illustrated by Leonard Shortall.
DESCRIPTION:“‘Don’t go there again!’ Chris’s father warned. ‘There’s something very strange going on at Black Rock Island.’
Chris and Addie are sure of that. For they have seen the two strange men- the tall one with the horrible grin, and the short one with the black, glittering eyes. Who are these two men, and what are they tryingto hide?
Chris and Addie are determined to solve the puzzling secret of Black Rock Cave.” (from the back cover)