The basic premise is very simple: the teenaged offspring of Lovecraftian horrors go to high school with humans. Wackiness ensues.
The ensuing wackiness is very important: in a show of complete disrespect for ol' Howie, mindblasting, world-devouring horrors from beyond space and time are played completely for laughs. You will save the Homecoming game from the rising of Cthulhu, use Elder Signs to fend off the products of the school cafeteria, travel through abhuman realms of twisted geometry in search of forbidden knowledge, and do it all in time to make it to Speculative Civilizations class in order to ask out that cute Byakhee who sits in the back row. Gibbering insanity is far less worrisome than being grounded, and being attacked by a multitentacled semi-corporeal monster is just an inevitable consequence of being caught necking with its daughter.