Weirdsister College has a network of pipes and valves installed as a means to absorb excess magical energy to help reduce the Foster's Effect during the week. This excess energy is released on Fridays, so students and staff must refrain from practising magic on Fridays, or the Foster's effect will be exponentially worse. A new professor, Starfinder, fails to heed the warnings. Millie, Cas and Ethel also ignore these warnings to near disastrous effect.