pulls into New Orleans and Jim greets it at the train station... unaware that two men are watching him from a carriage. When he enters the train, he hears woman complaining and finds a woman, Rosa Montebello, complaining to Artie, recently returned from his Washington assignment. Once Rosa storms off, Jim checks on his partner and discovers that he's wearing earplugs to block out Rosa's complaints. Artie explains that Rosa is the famous Italian diva and the niece of the Italian Minister. She's booked to perform the opera Lucia di Lammermoor
in New Orleans and Grant suggested that Artie give her a ride in the train. Rosa spent the entire trip complaining and now Grant wants Artie to act as an official escort during her three-day performance.
Outside, Rosa boards her carriage while the press write down her complaints. In the other carriage, one man, Igor, tells his employer, a golden-masked figure, that all of the arrangements have been made at the opera house.
Later, Artie tells Jim all about his adventures in Washington. They're interrupted when a messenger arrives with a wire from Governor Turnball's office. The governor would like Artie to attend a party in honor of his daughter Nancy. However, the dinner is at the same time as Rosa's performance. Jim offers to take Rosa in Artie's place, assuring him that Grant wouldn't want Artie to insult Turnball.
That night at the New Orleans Civic Opera, Rosa performs in the role of Lucia while Jim watches from a balcony booth. He notices someone watching from behind a curtain in a private booth on the other side. The masked man tells Igor to go and Jim notice the shadows shift. The curtain comes down abruptly and Igor arrives, ordering his men among the extras to bring her along. Jim slams through the wall and tackles them, while Igor is forced to flee. The thugs retreat as well, and one of them throws a spear hitting an extra. The man indicates the ring on his finger before dying and Jim takes it and discovers it has a unique insignia.
Back at the train, Colonel Richmond arrives and tells Jim that Artie is on his way to tell Rosa she's still in protective custody. The ring has a coded message in Italian referring to the Order of Lucia. Miss Ellen Collingwood, secretary to the chief of the New Orleans bureau, arrives and tells them that the dead extra is Pierre Deluc, who has been employed at the opera house for years and is charge of wardrobe. Deluc has no friends or relatives. When Richmond mentions the Order of Lucia, Ellen explains that three divas who have sung in the role of Lucia have disappeared in the last five years. Rumor has it that their ghosts now haunts the opera house. She suggests Jim check the Club Musique and he asks for Artie, but Richmond says that Grant has given specific orders that Artie accompany Rosa to Willow Manor for a reception given by the Crenshaw brothers, Karl and Max. Ellen has heard rumors about one of the Crenshaws but nothing definite. When Ellen worry that Artie might have his hands full, Richmond assures her that Artie has come up with a solution.
That night, Artie escorts Rosa to the reception... disguised as Colonel Vladislaw of Hungary. Artie plays the role of royalty to the hilt. Rosa is unaware of the deception, while Artie is unaware that Igor is watching from the balcony.
Jim goes to the club and listens to Angelique performing for the audience. Once she's done, Jim asks the bartender for an introduction to the Order of Lucia and shows him the ring. The bartender says that none of the members are there and Jim says that he'll wait. As the bartender goes in back, Angelique asks Jim where he got the ring. And he explains that he took it off of Deluc's body. Angelique explains that Deluc was her uncle and Jim presses her for answers. The singer admits that her uncle was involved in something but doesn't know what, and says that they need to talk privately at the opera house that night at 10 where it's safe.
As Jim walks out, he runs into two men singing on the street and briefly joins in. When he tries to move on, they trip him and knock him into an alley where more men are waiting. They attack Jim but he soon disposes of them and continues on his way.
At Willow Manor, Artie regales the crowd with tales of his life. Rosa, unaware of Artie's impersonation, is entranced by his charisma. Max escorts her on a stroll of the garden and Artie watches them go. He sees Igor, serving as a butler, and notices that the man is wearing an Order ring. Igor goes upstairs and Artie follows him, pretending to admire the paintings on the stairs.
In the garden, Rosa asks Max about his family and he explains that his brother Karl is a virtual recluse since he suffered an affliction. He turns the conversation to her role of Lucia and Rosa is eager to boast.
Artie goes upstairs and hears someone talking behind a locked door. Artie gets up on a chair and cuts open a small peephole in a window and sees the masked Karl complaining to Igor about how Max never thinks of him. One entire wall is taken up with a shrine to opera star Caroline Mason, who performed in New Orleans in the role of Lucia. Karl tells Igor to bring Max up and the butler reluctantly leaves. Artie replaces the glass in the peephole and hide, but the glass falls out when Igor emerges. The butler spots the footprints on the chair and realizes that there is a spy in the house. He notices a nearby wardrobe and confirms that it's locked from the outside, , and then checks a suit of armor. There's no one inside and Igor goes off to search. Once he leaves, Artie emerges from the closet, using a tool to open the outside lock.
Jim meets Angelique at the opera house and she takes him to the wardrobe room where Deluc spent most of his time. Before then he served with the entourage of Caroline Mason, who died in a hotel fire five years ago. Angelique doesn't know what Deluc had against Rosa but believes that something in the room had a powerful hold on her uncle. They hear someone outside and Jim looks outside onto the stage. Several thugs jump him but Jim knocks them down through a trapdoor. By the time he takes care of them, Angelique has fled.
The next morning, Jim and Artie meet on the Wanderer
and Jim explains that he went back to the club and no one had heard of the bartender or Angelique. They figure that the case revolves around Caroline Mason, five years' dead. Ellen arrives with Angelique's address and confirms that Artie is taking Rosa to a society bazaar that afternoon. She suggests that the agents confine Rosa to her hotel room but Artie is sure that the diva wouldn't listen... and that the agents are counting on the kidnappers striking again. Ellen is shocked that he would use her as bait but Artie admits he has no other alternatives... unless they can find someone else to take Rosa's place. She finally realizes that Artie means her and he convinces her to volunteer.
Jim goes to Angelique's home and discovers that someone has torn up the room. He finds a poster for Caroline Mason's performance as Lucia from five years' earlier and an A drawn in the powder on the floor.
Artie escorts a veiled Ellen out of Rosa's hotel past the adoring crowd and gets her into the carriage. They ride off and Artie assures her that the men who after Rosa won't follow them... yet.
Jim breaks into the opera house and goes back to the wardrobe room. Searching, he finds a lock with a pattern that matches the insignia on the Order ring. The door leads into a small room. A thug is hiding in the wardrobe room, slams the door shut, and activates the elevator that Jim is occupying.
Artie finally realizes that the driver is kidnapping them and feigns panic for the benefit of their captors. Gas pumps into the cabin and Artie assures Ellen that everything is going perfectly before passing out.
When the elevator stops, Jim emerges into the catacombs beneath the opera house. The agents hears someone singing and follows the music to an air vent. He finds a vast chamber with two of the missing divas trapped in gilded cages, while the masked Karl Crenshaw plays on the organ as Igor looks on. Angelique is chained to the wall. One of the divas is performing as Lucia and Karl dismisses her performance as inferior. He tells them both that Caroline Mason is by far their superior and that no one has sung as well before or again.
While Karl tells Igor to get rid of the two divas, Jim fires a dart and line across the chamber. Max and his thugs bring in the veiled Ellen and the unconscious Artie, and Karl tells Ellen that he will make her the singer that Caroline was. As Karl begins playing the area, Artie wakes up but feigns unconsciousness. Karl orders Ellen to remove the veil and then discovers that he's been fooled. Jim slides in and takes on two of the thugs while Artie trips the others and draws a gun on them.
Ellen struggles with Karl as he tries to grab her, and he falls onto a table below. Jim removes the mask and discovers that Karl is... Caroline Mason. She apologizes to Max with her dying breath. Max explains that he rescued Caroline from the hotel fire and it was her maid's body that was mistakenly identified as Caroline. The fire and smoke damaged her vocal chords, and Caroline vowed to make herself whole again by giving Max her voice by training another singer.
Later, Rosa is attending another reception in her honor. Jim and Ellen are there and discussing the waste of Caroline's death. Rosa comes over and assures them that they shouldn't feel uncomfortable among such distinguished company. She confirms that Artie isn't coming and then informs the disguised Artie that the horrid agent won't be coming. Artie assures her that he had hoped to challenge the offending agent to a duel and Rosa tells him that tonight is theirs as she snuggles up to him.