The episode starts with Henry refusing to put his ring bearer suit on for Polly and Paul's wedding at a bridal shop. Mum, Paul and Polly eventually then forced him to put it on. Back at home, Henry then lets Fluffy tear up his outfit. While watching Mutant Max, Mum interrupts Henry by turning off the TV, angry because she found out about the ripped suit. Unfortunately, Mum bought the last one, and it’s pink, making Henry say "No!!!"
The next morning, everyone put on their fancy clothes for the wedding, all except Henry. Mum and Dad chase Henry around the house and pulls him out from under his bed saying "It's Not Fair!" and makes him wear his ring bearer suit. It was raining outside everyone panicked except Henry. The family head off in their car but ran into some traffic. When they got to the church, Henry falls in the puddle and his family got all wet. Paul warns Henry that if he tries to ruin Polly's wedding, he'll get really really angry.
The wedding starts Henry and Peter holding two rings on each pillow until Henry steps on the train of Polly's wedding dress at the back, she tries to control herself and kisses him on the forehead. Henry laughed when Paul's full name is Peregrin but he tells him to be quiet. Henry plays around with the ring but loses and gives Polly his crocodile ring that he got as a prize in his cereal box which gave her a fright. Outside, Henry ruins every wedding picture and Dad takes him away.
While Paul gives a speech to everyone, Henry sneaks off and eats every bite of the cake. Paul chases him around and hits the cart and heads straight for Polly and cries. When Mum yells at Henry for ruining Paul and Polly's wedding, she says this is positively the last wedding she's ever taking him to . Henry was thrilled and thinks this is the best day of his life and shouts "YES!" ending the episode.
- Polly‘s wears pink lipstick, but in the next shot, her lips are plain, just like her original appearance when she's in her normal clothes.
- When Mum taps Henry on the shoulder at the end, Henry's suit is blue like the original one that Fluffy destroyed, not pink.
- In this episode, Peter says that Polly is his favourite cousin. But in Horrid Henry Eats Out, he says that Stuck-Up Steve is his favourite cousin. It shows that Peter loves everyone in the family.
- When Mum yells at Henry her lipstick was gone after she said “This is positively the last wedding I’m ever ever taking you to!”