Elsie Jones John Jack Young Mary Moore and George McDougal all live in service to a secret: Scotland Yard's best source of clues and leads is actually one of London's oldest coffee houses. These four young people manage the house as waitress clerk manager and owner-but they moonlight as England's finest undercover detectives.Therefore when a priceless portrait from a traveling Da Vinci collection goes missing they are the first on the job. Using their unusual set of sleuthing skills and with the unknowing help of their tale-telling customers they must track down the thief before he makes off with another great work without betraying their true identities to the patrons of the Oxford Street Coffee House.