Homicide and Old Lace The Avengers : Season 7 Episode 26

To celebrate his birthday 'Mother' goes to visit two elderly aunts to whom he tells a story from the Avengers' case files. It involves a criminal caper to steal art treasures. The treasures were to be held for safe keeping in an underground vault in the event of a national emergency but the criminals aimed to squirrel them away once in the vault. It is a hair colour changing story indeed.