Astounding Stories #184

When an alien rock creature literally crashes on Earth, John Travers, fishing nearby, unwittingly reassembles him. Revealing his race's ominous plan to plunder the Earth, he begins transforming a giant rock into a spaceship to report back to his world. Travers saves the day by blowing up Norkan and his ship. Luckily, the Highway Dept kept a box of dynamite and a detonator in a shack in the woods, secured by only a small padlock.