Episode 7 (S02E07)

Marlene is faced with a problem when some prize-winning racing pigeons are stolen – she’s allergic to birds. As a result, Al and Callum investigate the theft. They soon discover that the owner, Hugh McCoy, has been diagnosed with ‘Pigeon Lung’ – a rare condition that could kill him. His long-suffering wife Susan reckons that the person who stole the birds has done Hugh a favour. (BBC iPlayer)