A month after the events in "Parasite Planet," Hamilton "Ham" Hammond and Patricia Burlingame are married, and thanks to Burlingame's connections, the two have been commissioned by the Royal Society and the Smithsonian Institution to explore the night side of Venus. There they find a species of warm-blooded mobile plants with a communal intelligence that Burlingame nicknames Oscar. Oscar is very intelligent, quickly picking up English from Hammond and Burlingame. The humans learn that the Oscar beings reproduce by releasing clear bubbles full of gaseous spores. When the bubbles burst, the spores come to rest on another Oscar being, eventually grow into another individual, and bud off. In "Parasite Planet," the vicious, night-dwelling Triops noctivivans used these bubbles to attack Hammond and Burlingame, since the spores have a soporific effect on humans.