Edward is a wealthy gentleman in his early thirties who secretly operates as a master burglar and "putter-up" (criminal planner) in London. He utilizes his sophisticated appearance, chameleon-like ability to adopt accents, and wide array of upper-class contacts to fund and organize large-scale criminal operations. He sets his sights on a massive shipment of gold destined to pay British soldiers in the Crimean War.

Robert is a 26-year-old "screwsman," a specialist in lockpicking and safecracking. He possesses exceptionally nimble fingers and suffers from a chronic cough developed during a childhood spent dipping matchsticks in phosphorous. He approaches Pierce looking for work and takes on the highly specialized task of copying four specific safe keys.

Miriam is Pierce's intelligent romantic partner and a former actor. She leverages her talent for disguise, adopting varying accents and costumes to move smoothly between social classes. She uses Victorian society's underestimation of women to deflect suspicion while executing vital roles in Pierce's confidence schemes.

Edward is a coordinator of informants for Scotland Yard in London. He oversees undercover agents and gathers information from the criminal underworld. He believes strongly in his own intelligence and works to identify professional criminals operating in the city.

Richard works as a guard for the South Eastern Railway on the Folkestone route. He lives in poverty near a gasworks and cares for a sick child. His position gives him direct access to the luggage cars and the security protocols surrounding the bank's gold shipments.

Henry is a general manager at the Huddleston & Bradford Bank in Westminster. He oversees the transport of gold intended to pay British soldiers fighting in the Crimean War. He views Pierce as a respectable gentleman friend, completely unaware that his dinner conversation provides the blueprint for a major robbery.

Edgar is a bank partner at Huddleston & Bradford and the holder of one of the four essential safe keys. He is a creature of strict routine who enjoys competitive dog-ratting in public houses. He keeps a tight hold on his personal security and his family life.

Willy is an expert "snakesman"—a specialized burglar who excels at climbing walls and squeezing through small openings. Currently incarcerated at Newgate at the start of the story, he requires outside help to break out before he can offer his specific skills to Pierce's operation.

Barlow is a "rampsman" (mugger) who acts as Pierce's getaway driver and muscle. Recognizable by a prominent white scar on his forehead, he manages Pierce's fleet of cabs and stands ready to provide quick transport or physical intervention during operations.

Elizabeth is the 29-year-old unmarried daughter of Edgar Trent. Societal pressures label her past her prime for marriage, making her family eager to find her a suitable match. She is charmed by Pierce's apparent wealth and worldly stories.

Teddy is a well-dressed "swell" pickpocket who blends in with high society to steal from wealthy targets. He is hired by Pierce for a quick operation to identify the location of Mr. Trent's key.

Maggie is a young woman who lives in a London slum and works as a laundry thief. She is Clean Willy's girlfriend and acts as a messenger between him and Pierce's crew while Willy is locked up.

Bill is an Irish pawnbroker who secretly functions as an informant for Scotland Yard. He trades information to the police in exchange for leniency or cash, making him a known but risky contact in the criminal underworld.

Alice is Robert Agar's romantic partner. She operates as a petty thief in London, picking the pockets of distracted citizens during public celebrations.

Jonathan serves as an assistant to Edward Harranby at Scotland Yard. He helps process intelligence gathered from the network of informants spread across London.

Louise is a twelve-year-old girl who earns money as a laundry thief in the slums. She begins accompanying Clean Willy after he escapes from prison.