I could have decided to reread and review Donald Wollheim’s 1959 novel The Secret of the Ninth Planetas part of an epic reread of the entire SF series published by Winston … but I didn’t. I decided to reread and review this book because it happens to be one of the few books which fall in the intersection of the following sets: 1) books in which Pluto plays a significant role, and 2) books of which I actually have a copy . Today is, of course, the day when the American space probe New Horizons had its close encounter with Pluto, turning what was a dot on a photgraphic plate into this:
Go, applied science! And now, back to Pluto as it was imagined in 1959.
The years since Sputnik have seen great strides in manned  rocket travel to near space and the Moon, and in unmanned space travel to other worlds. As far as young Burl Denning knows, manned flight to other planets will have to wait until something better than the current primitive rockets comes along. What Burl doesn’t know is that the necessary advances in propulsion have already been made. Just not by humans.
Humans are not the first or most advanced civilization to develop space travel. One of humanity’s neighbors is working on a scheme that will doom life across the Solar System!