`Big School' features the goings-on in the dysfunctional staff room at Greybridge School. Chemistry teacher Mr Church has taught at the secondary school for years but is on the verge of resigning his position after his students react apathetically to a dramatic experiment he demonstrates. But the socially awkward educator puts his resignation letter in the bin following the arrival of new French teacher Miss Postern, who brings out the romance in him. She admits to enjoying having the attention of several of the school's teachers. Other teachers at Greybridge include would-be lothario PE teacher Mr Gunn, no-nonsense head teacher Ms Baron and geography teacher Mr Barber, who has been having a nervous breakdown for the last two years.