Smith packs on the blood and gore telling the story of an expedition searching for King John's lost treasure on the shores of the wild European East Coast marshes; the three-person expedition find a creature hibernating in the mud of one of the shores. They accidently awaken it, and it goes on a rampage, killing anybody or thing it encounters. The village not to far from the coast is terror-stricken, but the professor of the expedition is to busy trying to catch the creature, which they dub the "Slime Beast" for his own personal gain.
Smith keeps the plot tied around only a small group of characters, which means that the plot just about never jumps around from character to character. Focusing on a limited food supply for the beast works in Smith's favor, and the book never gets boring, even though my edition, the 1979 one, is only 110 pages long.
My only complaint about the book was that it seemed to come and go to fast; there really wasn't character development; it was just straight to the action. Doing so, in my opinion, just ruins the effectiveness of the book it self... Still, you'll finish in a couple of hours, waiting to see what Smith will come up with next.