Gary and Jonny have a very important client as they tackle the filth on a church entrance that's covered in carbon. Luckily, Gary is an expert in cleaning historic buildings — but can he salvage this one? Filth-fighting father Gary and son Jeff are taking on a carpet of moss in Hertfordshire. Years of growth needs to be demolished, but this duo plan to do their worst. And over in Edinburgh, Stephen, Liam and James hope to make a penguin pool pristine again. Can our dirt-destroying divers work their magic?