Terror Out of Space - Leigh Douglass Brackett

In the wake of unexpected meteor activity, a wave of inexplicable madness sweeps the already strange and ill-charted world of Venus. Racing to locate the source of the disturbance, Lundy and his team from Tri-World Police, Special Branch quickly find that locating the problem isn't half so tough as transporting IT back to headquarters. Out of his depth metaphysically and quickly sinking into the black pit of a Venusian sea, Lundy is about to discover his own profound reserves of strength and pit them against that which lurks behind a veneer of beauty-- the Unknown. - Summary by EVKesserich