In 1854, Edward Pierce, a charismatic and affluent "cracksman" or master thief, makes plans to steal a shipment of gold worth more than twelve thousand pounds being transported monthly from London to the Crimean War front. He faces enormous obstacles as the bank has taken strict precautions, including locking the gold in two custom-built safes, each with two locks, thus requiring a total of four keys to open. He recruits Robert Agar, a "screwsman" or specialist in copying keys, as an accomplice.