Hans is an old soldier, a refugee from post-war Germany. Patrick Riordan befriends him and learns his story.

When the old man is arrested and charged with war crimes in the camps of occupied Poland. Patrick and his father, Jack, set off for Europe to find Hans's missing sister, who can prove his identity.

Meanwhile, the real criminal is living in Florida. He flees after being recognised by a camp survivor and goes to ground.

In Europe, a group of old Nazis try to stop Jack and Patrick finding the truth and exposing the real perpetrator. They send men to kill them and the missing sister they have discovered.

They have not bargained on a man like Jack Riordan, and their attempts fail, However, their actions bring them to the notice of the Mossad that had been hunting them since the war's end.

Will they save their friend, or will the real criminal be brought to Justice?