Sally Lockhart (Billie Piper) has had some success as an investment advisor, but is taken aback when one of her clients demands restitution after an investment Sally recommended failed. It seems the ship carrying the commodities in which she invested disappeared on the high seas and the Lloyd's insurers have refused to settle her claim owing to irregularities. Sally is determined to recoup her client's funds and approaches the ship's owner, Axel Bellmann (Jared Harris), for the money. When he refuses, she enlists the help of her friends Frederick Garland (J.J. Feild) and Jim Taylor (Matt Smith), who have established themselves as detectives, to get to the bottom of it all. They learn that Bellmann is a ruthless businessman who has essentially bought his bride-to-be from a nearly bankrupt member of the upper class. He's also an arms merchant who has developed a new and very powerful weapon.
—garykmcd