It's the day of Pontypandy's new Ocean Rescue Centre launch and Station Officer Steele is taking the firefighters on a tour of the centre. As they arrive on the quay, so does the new coastguard, Ben Hooper.

As twins Sarah and James can never agree on what kind of birthday party to have, Bronwyn has decided that this year they will have two parties. James' will be a science party and Sarah's will be a football party.

It's the annual Pontypandy Cheese Roll Challenge (a race down a hill chasing a giant circular cheese) and Norman really wants the prize - the giant cheese! He sets out to win, but is it too late to enter the competition?