Plot summary
The Alloy of Law is set in an analog to the early 20th century, on Scadrial, approximately 300 years after the conclusion of the original trilogy. [2] It also introduces the concept of Twinborn, beings naturally born with one allomantic and one feruchemical ability, for the first time in the series.
Lawman Waxillium Ladrian and his partner Lessie are investigating a serial killer in Feltrel, a small town in the Roughs. They decide to split up and Wax follows the murderer's tracks, leading him into a small church, where he finds that Lessie had been captured and held hostage by the serial killer. While trying to free her, Wax accidentally kills Lessie.
Five months after the death of Lessie, Wax has given up the role as peacekeeper, and returned to Elendel, where after the death of his uncle and sister (who were involved in a carriage accident), he has become the head of his house. Due to his uncle's inadequate financial operations, Wax is trying to save House Ladrian from bankruptcy. The only way to do it is to find a suitable high-born lady from a financially stable house to marry.
Just before meeting with promising prospect Lady Steris and her father, Wax is unexpectedly visited by his friend, deputy, and master of disguise Wayne (who is also a Twinborn with the abilities to create speed bubbles, and store health in his goldminds), who has come to Elendel to investigate a series of robberies and kidnappings for which a rogue band called "the Vanishers" is responsible. He wants Wax's help to solve the case. Although still torn between his previous life as a lawman and his obligations to House Ladrian, Wax declines to join him. During the meeting with Lady Steris, her father, and her half-sister Marasi (who is posing as a distant cousin to Lady Steris, for she is illegitimately born), Wayne pretends to be Wax's distant uncle. Wax and Lady Steris come to an agreement to marry after several months of courting, and to introduce themselves as a couple to the elite society.
At a wedding party held by House Tekiel, the Vanishers show up and try to kidnap Steris and Marasi. Wax and Wayne, working as a team, manage to save Marasi, and kill most of the Vanishers when the event becomes violent. However, their leader and a few others slip away with Steris. Wax decides to solve the case and rescue his wife-to-be. After a careful recollection of the events at the wedding, Wax comes to the conclusion that the band is led by a former lawman named Miles, who is a Twinborn with the ability to cure any injury almost immediately.
Wayne discovers the bandits' hideout after interrogating one of the captives in police custody, and meets with Wax and Marasi in House Ladrian's mansion to share his findings. There Wax's butler tries to kill him, but the trio manage to escape.
Wax and Wayne, accompanied by Marasi, go to the bandits' hideout, and find it deserted, with minimal remaining evidence. They visit an old acquaintance – a gunsmith named Ranette - and form a plan to capture the bandits during their next robbery.
Wax deduces that the Vanishers will try to rob a train transporting large amounts of aluminium (which is extremely valuable due to its immunity to allomancy). He manages to slip into the cargo hold of the train. Meanwhile, Wayne and Marasi watch as the bandits switch the train's carts, and manage to follow them to their new hideout. There, after a long battle, in which all the bandits except Miles are killed, Wax and Marasi manage to distract Miles long enough (with Marasi's Allomantic ability to slow down time inside a speed bubble) for Wayne to fetch enough law officers to subdue and capture Miles. Lady Steris is saved, and although Wax feels attraction to Marasi, he decides to continue with the planned marriage.
Wax discovers that the person who had recruited Miles in the first place is the presumed dead Lord Edwarn Ladrian, Wax's uncle, who still holds the other kidnapped women. Edwarn is connected to a shadowy organization known as the Set, and has used the robberies to commit profitable insurance fraud. Wax and Wayne decide that they will stay in Elendel and try to stop Lord Edwarn and his organization from fulfilling their plans. Miles is stripped of his metalminds and publicly executed. Marasi is approached by Ironeyes (Marsh, now revered as Death himself) and given a mysterious book.
