For Gabriel and his beautiful Venetian-born wife, Chiara, it was supposed to be the start of a pleasant weekend in London a visit to an art gallery in St. James's to authenticate a newly discovered painting by Titian, followed by a quiet lunch at an Italian restaurant along the Strand. But a pair of deadly bombings in Paris and Hamburg has already marred this sparkling autumn day. And while walking along Wellington Street, the ever-vigilant Gabriel notices a man ...