Contamination Crew by Alan E. Nourse, Science Fiction, Adventure (Hardcover)

Orders are orders! The creature had to be killed. But just how does one destroy the indestructible?

Three months ago, as crew of the General Practice Patrol Ship "Lancet," my colleague Green Doctor Wallace Stone and myself began investigating certain peculiar conditions existing on the fourth planet of Mauki, Vorochislov Sector. The entire population of that planet was found to be suffering from a mass psychotic delusion of rather spectacular proportions: namely, that they and their entire planet were in imminent danger of being devoured, in toto, by an indestructible non-humanoid creature which they called a "hlorg" . . .