A penniless Countess poses as a charitable lady, but instead, she leads a ring of unstoppable jewel thieves with a flair for breaking and entering into the houses of her careless rich guests.
Agents in Steed's department are being fooled into giving away secrets, by men posing as Army officers at a fake Government training establishment. And their next victim is... Tara King.
Murder in Hatton Garden and Steed and Cathy learn that diamonds are no longer a girls best friend.
