The diamond mystery

Somebody is stealing diamonds from the jeweler Mohammed Carat! It looks like the culprit is someone on his staff, but who? Is it Luke Smith, the recently hired fitness fanatic with a taste for the finer things in life? It surely can't be Vivian Leander, the loyal shop assistant who is now short of money... The police in the little town of Valleby are stuck, so they contact young detectives Jerry and Maya, classmates who run their own detective agency. Will Jerry and Maya be able to use their detective skills to find the thief? As they well know, even a tiny clue is worth its weight in gold.