The trouble starts when Del agrees to provide painter and decorator Brendan O'Shaughnessy with enough louvre doors to refit an entire housing estate in Nunhead.
Del's supplier, Teddy Cummings, only stocks and supplies in bulk, so it's up to the Trotters to find two grand by the next day or there's no chance of getting the doors.
As usual, a solution turns up in the form of Denzil's redundancy money, which they somehow convince him to part with, only to be told by O'Shaughnessy that the doors he's bought aren't needed. And to make things worse, the doors turn out to be stolen.
It's not long before Denzil and his five brothers come looking for their money, so with nowhere else to go, the Trotters visit their mother's grave - a favourite refuge for Del in times of trouble.
At their mother's graveside, Rodney notices a rare butterfly from the cover of his magazine, that's worth about 拢3,000 to collectors. After chasing the butterfly around the churchyard, the park and the boating lake, they finally capture it, only for Denzil to wander past and squash it.