Jack Rimmer is put in charge of failing, inner-city comprehensive Waterloo Road when the previous Headmaster has a mental breakdown in front of the entire school. He hires Oxbridge graduate Andrew Treneman, a man more familiar with the upper class, hoping he can improve their failing status and bring them back from the bottom of the league tables. English teacher Tom Clarkson is having second thoughts about his marriage to Lorna Dickey, instead finding himself falling for Drama teacher Izzie Redpath. Donte Charles, a rebellious pupil, strikes up trouble for Izzie's daughter, Chlo.
Waterloo Road Comprehensive is on the scrap heap and when the Head Teacher, Mr Vaisey , has a nervous breakdown, his deputy, Jack Rimmer is reluctantly thrown into the hot seat. Jack is only too aware that Waterloo Road is at the bottom of the league tables and he’s under pressure to make an improvement, and fast. He begins by taking a huge gamble and recruits optimistic, educational zealot, Andrew Treneman, who wants to give up his comfortable private school job in exchange for bringing the benefits of his elite education to Waterloo Road.
Oxbridge-educated Andrew is convinced that strict discipline is the only way to turn the school around and he starts as he means to go on when he spots troublesome pupil, Donte Charles, stealing another kid's bus pass and immediately calls the police. Back at Waterloo Road, Jack is incensed when he discovers that Donte has been arrested, especially when he learns that his new Deputy Head is the “daft, have-a-go hero” who made the complaint. Andrew also goes on to clash with art teacher and Head of Pastoral Care, Kim Campbell. She thinks he’s way out of his depth with the Waterloo Road kids, and she may be right.
English teacher Tom Clarkson’s life is a mess. He’s about to be married to his live-in girlfriend and fellow teacher, Lorna Dickey, but can’t seem to find the words to tell her that he’s no longer in love with her. With the wedding fast approaching, Tom panics and hastily calls it off. Lorna is understandably distraught and pleads with her best friend, drama teacher Izzie Redpath, to get the truth from Tom. Is there someone else? Izzie does as she is asked and quizzes Tom over a lunchtime pint. She gets the shock of her life when he reveals that there is someone else – her.
Izzie's youngest daughter, fourteen-year-old Chlo Grainger, has been seduced by Donte's wild ways, much to the worry and consternation of her mother. Andrew is also less than impressed with Donte’s behaviour, and things come to a head in English when he confiscates Donte’s phone, unaware of the fact that his father, Clarence, is listening in. He turns up at the school in a rage and begins laying into Andrew in front of the whole class. Jack is showing around a couple of prospective parents at the time and is forced to cut short the visit in order to break up the fight. The parents leave, the police are called, and Clarence is arrested.
Clarence has a previous record of violence and the police are sure that this time, he’ll be sent down for a long time. Kim is concerned about this, not least because Clarence is a single parent and that while he’s in prison, Donte will be forced to go into care. After a lengthy debate with Kim, Andrew agrees to drop the charges against Clarence, but only on the condition that he apologise for his actions in front of the entire school. Far from being relieved that his father has escaped a jail sentence, Donte is furious when his supposedly ‘hard as nails’ old man humiliates him in front of all of his friends – there’s no way he’s ever going to live this one down.
Having come to terms with the fact that he has no chance with Izzie, Tom reluctantly decides that the wedding is back on. Although Izzie is pleased that Lorna is happy again, her smile hides a painful secret – Tom’s revelations have forced her to realise the hidden depths of her own feelings for him, but there’s no way she can break the heart of her best friend. Somehow, she manages to make it through the wedding, but the sight of Tom and Lorna taking the floor for their first dance is almost too much to bear. However it soon transpires that this is the least of Izzie’s worries. Her ex-husband, Jimmy, has deserted his baby-sitting duties, leaving their daughters home alone. Tom finds a tearful Izzie waiting outside for a taxi. He’s more than happy to provide comfort and before long, they’re sharing a kiss.
The party also comes to an abrupt end for Jack when the police call him into the school – there’s been a break-in and the hall has been trashed. As he and Andrew survey the damage, Jack realises that he has finally reached the end of his tether as far as Waterloo Road is concerned and can no longer see any point in carrying on. But Andrew is still determined to make a difference and knows that deep down, Jack is too. Meanwhile, Donte has stolen his father’s limousine and decides to take Chlo and their mates, Holly and Adam, on a high speed joyride. However this time, his hell-raising is about to have terrible consequences…