The trilogy concludes--following up the charming but inept Guardians of the Singreale (1982) and the mostly ludicrous Star Riders of Ren (1983). Graygill welder Raccoman Dakktare and his wife Velissa return from Rensland with the news that the evil Thanevial (he has stolen the magical diamond, Singreale) and his army of sulfurous Dregs is approaching Graygill-land via a submarine tunnel. Meanwhile, some Graygills--the cave-dwelling Moonrhymes--have resisted the foul Blackgill Parsky's assaults and have hatched a couple of giant fire-breathing salamanders as allies. But Thanevial's tunnel leads straight into their caverns; soon the lower levels are swarming with Dregs. And so Raccoman and Velissa, aided by some friendly Star Riders, set about organizing defenses and disposing of Parsky. . . before the final showdown with Thanevial. Technically superior to the previous books--with some lingering charm in the early chapters, long-winded and unsurprising battle heroics later on: a pleasing conclusion, overall, for Singreale fans.