Mr. Hammond is desperate to win a football trophy so tells PE teacher Mr. Hogan not to pick Roy for the team. Mr. Hogan has to make up a reason and suggests to Roy he needs to improve his fitness but Roy gets the wrong impression and believes he needs to lose weight. His fitness efforts leave him with an even slimmer chance of making the team.

Roy really wants to have a pet dog but his parents say he isn't responsible enough. At school Kathy teases Roy about this but Roy's friends tell him she is scared of dogs so he decides to pretend to be one and chases her around the hall. However Roy's act becomes more convincing than anyone could expect.

After yet more mishaps Roy's parents and friends try to boost his confidence and self-belief. However things go so far that Roy becomes so admired that his head literally becomes bigger. It fills with extra knowledge and he unexpectedly becomes an expert on everything - surely the person who can make sure that the school wins a vital quiz that is so important to Mr. Hammond?

Roy feels left out at school because all the other children are growing up, including getting spots. He binges on junk food and doesn't wash to try to get a spot but when he eventually succeeds it causes him trouble he could never have expected.

Bill's elderly Aunt Bridie dies and the family want to know whether she will be leaving her money to them or to Bill's flash brother Danny. Roy's special skills might help them find out the answer.

Roy seems even more accident-prone than usual and his family are desperate to keep him out of harm's way. However they can't prevent another mishap which results in him being shrunk down to five inches tall. While this has its advantages it also has its share of problems and might put his parents' anniversary plans in trouble.

It's Valentine's Day and against the odds Roy starts to feel attracted to arch-enemy Kathy, upsetting Sinead. It seems Miss Sheringham has had a card and been invited out by Mr. Hammond but how does she feel about his interest? Becky feels good after receiving a card unexpectedly but who is her secret admirer?

Roy damages his dad's car when a skateboarding trick goes wrong but soon things get even worse. He tries to put things right by getting a Saturday job and working for magician Magical Mickey but will it be just the trick or not so magical after all?

Jack is behaving strangely, showing no interest in football and snapping at his friends. Roy tries to find out the reason by following him but gets spotted. However Roy makes a remarkable discovery with a rubber and finds a way that he can find out the truth about Jack - and have other fun as well.

Roy's dad Bill likes to think of himself as a DIY expert and lands himself a decorating job for Mrs. Sweeney and Roy is keen to help. However Mrs. Sweeney is a fearsome woman and Maura and Becky are scared in case Bill and Roy fail to do a good job.

Roy feels left out because he doesn't have a new computer game unlike his classmates. A bad angel appears on his shoulder suggesting he get hold of it in the wrong way but a good angel warns him not to. Which way will Roy turn?

Mr. Hammond injures himself when one of his science experiments goes wrong. He decides to stop teaching science for a while but recruiting a substitute teacher is difficult. However Roy feels he has the solution in his Uncle Troy but there's something about Troy that makes Miss Sheringham believe he isn't all he seems.

An inspector - Marjorie Hegarty - arrives to do a review on Roy's progress. Mr. Hammond is worried but not for Roy's sake unlike the children and Miss Sheringham. The review brings to mind much of the mayhem Roy has been involved in. Will Ms Hegarty decide that Roy needs to leave Ballyfermot Primary and go somewhere else?