When Milly's teacher has to have a bunion removed, the class gets a substitute teacher for the five weeks she'll be gone.

But Mr Wright is not like any other teacher Milly has ever had. He's convinced he's always right (of course!), is super strict and obsessed with PE. So much so, he convinces their principal, Mr Manley, to allow their class to organize a Lá Spóirt for the whole school. Mr Wright's competitive spirit rubs off on Milly and soon she's taking part in the egg and spoon race, the three-legged race and even a bit of archery.

Sure, what could possibly go wrong?