Life is never fair to 11-year-old Alistair Fury. Sean, his Irish dad,is loving but lazy and his mother Celia too self-absorbed in her T.V. cookery show to give him any time. This leaves Alistair open to his bullying siblings, drippy Mel, who is in love with a different,unsuitable boy, each week and the body-proud but thick-headed Will. They refer to him as Alice,thus compelling him to get his own back with his gang of 'Revengers'. The family's insistence on an economy drive means that Alistair has to eat cheese on brains, but the perfect revenge opportunity arises ...
Celia is filming a live cookery programme from her kitchen and has agreed that Alistair should help her but, thanks to Mel and Will, he ends up in disgrace and they take over as their mother's helpers. Alistair has the ultimate revenge planned - letting loose a snake, rats and a box of stick insects to add to the broadcast.
When Sean and Celia go away for the weekend they get Granny Constance, Sean's mother, to come and baby-sit, but she is easily bribed by Will to leave the Furys on their own. Alistair is banished to the shed by his bullying siblings but he well and truly pays them back as his advice to botox-obsessed Mel leaves her with very swollen lips and Will, out to impress a girlfriend, ends up in his best suit but covered in a bucketful of gunge Alistair has rigged up to tip all over him.
Alistair and his fellow Revengers' night under canvas in the Furys' back garden is rudely interrupted by Mel and Will pretending to be monsters to scare them. Alistair retaliates by creating a monster of his own and, for added good measure, hopes to make his siblings pay by staging his own death at the hands of the monster.
Alistair is in a queue at the computer shop, where he has been sent by Will to get him the latest computer games console. With nothing better to do, Alistair starts chatting to a little girl and explains to her the importance of technology if one is to be a successful Revenger.
It's bad enough that Mel and Will are always in and out of his room , disrupting his privacy, but now Granny has borrowed Alistair's bed while Sean gives her driving lessons. Not that there is a current family car, since Sean sold it and hopes to come up on the Lottery to buy a new one. Alistair decides to help him, if only to get rid of Granny.
When Will falls ill he milks the situation and carries on the pretence of illness so that Alistair has to do his paper round. Like the good Revenger that he is Alistair prints his own paper, exposing Will's deception, and pushes it through every letter-box in the street.
Granny is having a family group photograph taken to celebrate her seventieth birthday but decides that Alistair looks too scruffy, in his Dr. Revenge T-shirt, to be included in the line-up. Alistair sets out to sabotage the sitters, dying Will blue in his shower, setting up Mel for the haircut from Hell and revealing that Granny is bald and wears a wig. Soon Alistair is the only person who looks fit to have his photo taken.
Alistair tries to master the art of hypnotism, mesmerising Mel and Will into becoming his slaves and obeying his every wish. Unfortunately he has failed to realise that he too was hypnotised at Ralph's party so that he behaves very oddly every time that he sees Pamela Whitby - well, more oddly than usual - taking fright at a bunch of flowers and sitting in a tree with a dog that thinks it is a cat.
Psychiatrist Dr. Tara Lyer appears with Celia on the television programme, 'Ask the Not Quite an Expert', and Will becomes so love-sick for her that his school-work suffers, making Alistair the brains of the family, with Sean promoting him to his Number One Son. Dr. Lyer believes that Will is suffering from 'middle child syndrome', for which the only cure is for the family to stop being nice to Alistair. However Alistair has some psychological tricks of his own to see off the so-called expert.
Alistair enters music teacher Mrs. Muttley's talent contest, The M-Factor, as a pianist, in the hopes of impressing his beloved Pamela Whitby. However, he is no pianist and cheats by hiding a tape recording in the piano. Sean and Celia are sent on a false trail to stop them attending but Mel and Will also enter the contest as Thrash Punk Noise. Who will win, and will Alistair's deceit be exposed?
Granny tells Alistair that every generation of the family has an 'Alistair', essentially a loser who comes to no good. However, there is a happier family tradition. A precious ring,currently owned by Granny, gets passed down to the first child of their generation to get engaged. Alistair inevitably sees this as his chance to get engaged to Pamela Whitby but confusion arises when he finds himself with a second betrothed.
When Mel and Will steal his pocket money Alistair can't afford a Father's Day present for Sean or a pair of designer trainers, so he and the Revengers resort to robbery, holding up Mel's latest - feeble - boyfriend as he walks her in the park. Eventually Sean buys Alistair his trainers but when he takes them to school vengeful Miss Bird makes sure they go off with a bang.