Arnold Chetwode never intended to become involved in international intrigue. He was gently bred and fell upon hard times after his father made a bad investment and died soon after; he goes to London to make his fortune. A surprising invitation puts him at the right time and place to be a witness to a public murder. His employer and employer's family are involved in the aftermath. is anyone who they seem to be? Even Ruth, the poor invalid who befriended him when he was penniless. Mystery upon mystery follows, for the plot concerns an attempt to bring about a revolution in Portugal.