It will prove to be one of Batman's most challenging adventures as a new hero joins the Dark Knight's continuing cast of characters in BATMAN: SWORD OF AZRAEL. Azrael is the enforcer for the secret Order of Saint Dumas, a society whose existence dates back to the time of the Crusades. When this bullet-riddled angel of death crashes into the midst of a Gotham City parade, Batman is drawn into the mystery of Azrael, launching them on a quest that leads both Batman and the young Azrael to Europe where they separately investigate the systematic slaying of the members of the Order of Saint Dumas.
A man clothed in Medieval garb who identifies himself as "Azrael" attacks a man by the name of LeHah with a flaming sword, claiming the latter guilty of being a "liar", a "traitor", and a "defiler". LeHah, however, shoots the assailant with Teflon-coated bullets that bypass his bulletproof costume. Though Azrael is able to scar LeHah with his sword, he is ultimately overpowered by LeHah's bodyguards and is shot multiple times, sending him tumbling out of LeHah's penthouse and into the streets of Gotham, disturbing Gotham City's annual Founder's Day parade.
In the ensuing chaos, Azrael is able to commandeer one of the parade's horses, and makes his way to the home of his son, a blond, bespectacled university student. As he does so, the dying man strips himself of his costume, explaining to his son that "Azrael" must be kept a secret. He further requests that no doctors are to be called for him, and his corpse must be stripped bare and left for strangers to find. Lastly, he tells his son to open a package that he had left for him earlier, stating that it contains "what you will need", and urges his son to not fail where he, his father, had. Seconds later, the man dies.
Bruce Wayne, meanwhile, has taken an interest in the "Vanishing Angels and Sudden Death" that had disturbed the Founder's Day parade - especially since the penthouse of Carlton LeHah, an arms trafficker with no recorded past, was right above the scene when it started. As he changes into his Batman garb, Bruce states to Alfred that police had discovered a bulletproof vest - part of Azrael's costume - near the scene of the parade, and goes on to mention that the vest had been riddled with bloody bullet holes. The Caped Crusader wonders aloud how much willpower it would take for a man to keep himself alive, let alone conscious, with so many injuries.
As time passes, the university student obeys his father's wishes, and finds in the package a telephone number, forty thousand dollars in cash, and a letter instructing him to fly to a small airfield in Switzerland. After calling the number, and summoning two mysterious men that remove his father's corpse, the university student obeys the letter's instructions, and meets a man at the airfield who drives him to a small village. It is at the village that the student meets a dwarf by the name of Nomoz, as well as a giant named Heinrich. Nomoz explains that he is a teacher of "The System", and goes on to mention that the student's dead father was a member of a secret organization that dates back to the Fourteenth Century - an organization that he and Heinrich will prepare the student to join.
Back in Gotham, Batman continues to investigate LeHah's penthouse, and places a special laser microphone outside the window. Soon enough, the microphone picks up details of an arms exchange between LeHah and a man named Lescault that is to take place in a Swiss village known as "Lucerno". At said village, Nomoz shows the university student a medallion bearing an intricate design - the symbol of the Order of Saint Dumas, which, according to him, will turn the student into a "bringer of death". In the meantime, Commissioner Gordon meets with Batman, and informs him that witnesses claim the "Vanishing Angel" at the parade has held a sword when he entered an alley, only to come out of said alley empty-handed. The Caped Crusader investigates the alley in question, and finds Azrael's discarded sword on the steps of a cellar - a sword that bears the symbol of the Order on its hilt.
Little does the Batman know, however, that an ocean away, Nomoz is using the same symbol to put the university student through a brainwashing process to transform him into the next Azrael. When the student awakens, he is able to subdue Heinrich in a fight without even consciously thinking. Nomoz explains that the student's father had been utilizing hypnosis sessions on him since infancy - he already has all of the skills and knowledge to become Azrael within his subconscious; all that is left now is the physical training. Back in the Batcave, Bruce and Alfred learn of the symbol's origins from Barbara Gordon, AKA Oracle: the Order of Saint Dumas was a splinter group of the Knights Templar, who had continued the Crusades long after their "official" end, became wealthy from the loot they pillaged, and vanished by the Fifteenth Century - the prevailing theory being that they had retired to Switzerland to enjoy their riches.
As Nomoz continues to train the university student and informs him of the fact that his grandfather, great-grandfather, etc. had all been part of a long line of Azraels, Bruce Wayne and Alfred Pennyworth set course for Switzerland, determined to find the link between LeHah and the Order of Saint Dumas. The two eventually make it to the tiny village of Lucerno by helicopter, passing over the very chalet where Nomoz is training the next Azrael.
Just as the chopper prepares to land, however, LeHah fires an experimental missile launcher - the focus of his arms exchange with Lescault - at the chalet, destroying it in a burst of flame.