Traeih, a planet terraformed eons ago, now hosts two distinctly different species of humans. The jovial, subterranean livelihood of the Perigiens contrasts a cultural extreme to the sanatorium obsessed Apogiens, who reside above ground. Centuries of technological differences defined inside and outside the human body, stretch the species further apart. At stake in Cuckoo-spit and the Froghoppers are the connections we hold to humanity, individuality and love.

Carrie-Anne, a young Apogien woman, escapes authorities and is subsequently kidnapped by the Froghoppers, a secret fringe group of Perigiens. On Perigiee, separated from home, she is thrust between worlds. Renamed and swifted away, her disappearance spurs political upheaval and upsets the balance of power in a way not seen on Apogee for several millennia. Literally defying gravity, the Froghoppers introduce their new inductee to a mind-bending tour of perception to change her thinking forever.