Elderly retired surgeon, on a holiday in Alfriston, a village in Sussex, finds a first edition of Gray's Anatomy in a second-hand bookshop. He discovers that written in the title page were the signatures of two previous owners.

The second owner turned out to be Harry Quatermain who joins the Royal Army Medical Corps. Harry is dispatched to join the brigade at Peshawar where a war waging for control of the Khyber Pass.He then is promoted to brigadier and head of the RAMC in the taking of Jerusalem in 1917.

A mortally wounded Arabian soldier dies in Harry's hands but not before he hands over a screw top tube the contents have a message could influence the outcome of the war.He then hides the container and contents leaving a cryptogram for others to decipher it in the future. The rest of the story describes the consequences in Israel, England and Azerbaijan of deciphering the message in the current era.