'William and Elizabeth discover passports in a secret library, in which they are instructed to write their names and be transported back in time. They travel to the year 1415, the time of King Henry V, king of England, who intends to claim the French crown as his own. The twins befriend a young squire, Hugh Calthorpe, who serves the great knight, Sir Thomas Erpingham and together the three friends sail to France and become entwined in the siege of Harfleur and witness first hand the Battle of Agincourt. Whilst warned not to meddle in events of the past, William and Elizabeth are definitely not going to simply sit on the sidelines and watch. They’re very much involved in history.' (Publication summary)