MumDem follows the story of four lads born and raised in the Welsh capital of Cardiff, with dreams of making it big in the fashion industry. They plot; they scheme, and do their best to acquire a lady friend or two, who must be at least fifty years old - Atmosfear, self appointed leader of the gang, tries to keep them all afloat financially with their own brand of clothing, MumWear. But however worldwide Atmosfear likes to think it has become, MumWear never actually leaves the South Wales Valleys. The MumDem spend their days listening to Atmosfear dictate their way of life at their local with Brian the barman, who attempts to be a father figure to this group of delinquents. Ultimately, the goal is to land the 'Ultimate Mum' and sell the MumWear clothing range for a fortune, and finally amass the 'MumWear Millions'.