03 - Operation Terror by Murray Leinster

In a shocking turn of events, an unidentified spaceship descends into a serene Colorado lake, unleashing a terrifying paralyzing ray weapon. As the creatures from beyond begin abducting humans, a determined land surveyor and a tenacious journalist find themselves trapped within an Army cordon that is powerless against this enigmatic foe. Will they uncover the aliens sinister motives and thwart their plans before its too late? (Summary by Mark Nelson)