Donizetti's "Lucia di Lammermoor" is well-known for the opera's climactic mad scene in which the heroine murders her husband before falling into insanity.

The opera features a total of three deaths from characters onstage, but death is a major theme that resonates throughout with Lucia narrating the death of a young woman, Edgardo talking of his relatives' death at their tombs and Enrico noting that his mother has recently passed on.

The craziness onstage usually provides for a tremendous evening of glorious music and acting, but on April 4, the Metropolitan Opera's presentation provided its own series of backstage madness.

Tenor Joseph Calleja started the evening despite missing out on Wednesday's performance due to illness. He had been sick throughout the evening and some wondered whether he would even perform on Saturday. His middle register sounded as glorious as usual, with the warmth and brightness that the Maltese tenor emits with relative ease. But in the upper register, Calleja could not manage to project without a raspy sound interfering with his tone. And it was not just one isolated incident but a number that forced the singer to restrain himself as the duet with Lucia wore on. By the end, the singer was cupping his ear while singing, almost as if trying to hear himself.

By the time the second act was ready to go, an announcement was made that Salvatore Cordella would replace Calleja, who was struggling with the illness and side effects from the medication.

Cordella's warm up? The famed sextet "Chi mi frema in tal momento." He projected with a nasal sound initially, but his voluminous voice and confident phrasing more than made up for it. He was especially effective in Edgardo's most piercing moments, particularly when he interrupts Lucia during the stretta ("Ah! Vi disperda!"), where he rose to the climactic B flat powerfully.

He was also potent in the Act 3 confrontation with Enrico, his voice growing in strength alongside Luca Salsi in what became a battle of wills expressed by gradual crescendos and sharper attacks on consonants. By the end of the exchange the two were verbally battling, looking to one-up the other vocally.

But things got a bit eerie in the final act, at least briefly, when Cordella had to sing the final double arias. He stood all the way up stage with his back to the audience singing the opening recitative. At one point he seemed to flub his lines but continued on, his back still to the viewer. Then as the horns signaled the start of the aria "Fra poco a me ricovero," he ran off stage, leaving the viewer rather confused. Suddenly he reappeared during his opening lines, singing with elegant legato, his voice eventually rising to a tremendous fortissimo in the aria's final cry of pain. He had a more delicate and measured tone during the second aria "Tu che Dio spiegasti l'ali," his voice growing quieter and more detached as he plunged to his death.

Another interesting bit of suspense took place less publicly. Earlier in the day, Salsi subbed in for an ailing Placido Domingo in "Ernani." And then he took the stage as Enrico. Most singers do not sing two lead roles in a single day and certainly not a few hours apart. But Salsi was not only up to the challenge on both fronts, but excelled wonderfully.

For one reason or another, many baritones struggle in the opening aria, often losing clarity of sound in the upper registers. It certainly is a tough ask, especially considering that it is the first thing the baritone tackles. But Salsi had no qualms whatsoever. He sang every line with utmost polish, emphasizing Enrico's position as a nobleman. He delivered "La pietade in suo favore" with quick bursts and accents, providing a counter to the more reserved singing of the preceding number. During the duet with Lucia in Act 2, the violent nature started to grab hold; there were very few moments of delicate singing or even tenderness toward his sister. It became obvious quickly that Salsi's take on the character was a brutish man who overpowered his sister not with emotional manipulation but with more physicality.

During the famed sextet, his piercing glare at Edgardo was perhaps the most tense-filled moment of the scene while his aggressive singing during their Act 3 confrontation was the ultimate consummation of his predatory nature. Even in the mad scene when he made his appearance, he was a man full of anger, almost unable to accept his sister's crisis.

While the men got headlines for some heroic feats, it was Albina Shagimuratova who made her own waves with some of the most polished singing the Met has seen in quite some time. Every single line flowed and rang with ease. The phrasing was fluid, with every crescendo and diminuendo providing its own musical narrative. Her singing during the opening aria "Regnava nel silenzio" started off quietly but grew gradually with the intensity of the narrative until her voice climaxed in a glorious high note that slowly withered and faded. There was a delicacy in the delivery that immediately made her Lucia's weakness clear for the audience.

This warmth of sound contrasted greatly with the more vicious performance from Salsi and the fiery Cordella, continually showing Lucia's frailty as a source for her eventual madness. In the famed mad scene, she maintained the polish of sound, which while far from violent or detached, had an otherworldly quality. This coupled with her innocuous stare into nothingness made for a convincing display of Lucia's madness. During the connecting passage between the larger "aria" and final cabaletta, Shagimuratova showcased the first truly violent outbursts of Lucia's damaged psyche. As she glared at her brother and called out "Chi mi nomasti? Arthur!" she delivered a fierce accent on "Arturo" before keeling over in pain. At the height of this passage, she looked into Enrico's face and seemed to recognize him for a moment; in this instance she let out a pinched cry of horror, a gesture that has become increasingly traditional in modern-day renditions of the role. The final cabaletta had a sardonic quality to it, with her phrasing have a more detached nature, the pauses between notes becoming more paused. The coloratura in these moments became more frenzied with pronounced swells throughout.

As Raimondo, bass Alistair Miles was a gentle Raimondi. He was subdued during the duet with Lucia, his voice tender throughout. But when he came in between Enrico and Edgardo after the sextet, his voice boomed throughout the theater as the man of reason. However, he was frail in his "Oh! Qual funesto avvenimento!" He sang quietly, almost as if he was afraid to relate what he had just seen, thus forcing the listener in and adding greater suspense to the narration.

At the podium, Maurizio Benini delivered a refreshing account of the bel canto score with swifter tempi than normally delivered. The speed of the scene preceding the famed sextet added urgency to the scene and the relentless drive of the duet between Edgardo and Enrico ratcheted up the tension. The explosions of sound at the start of this particular scene really drove home the sturm und drang.

Harp soloist Mariko Anraku deserves tremendous applause for a breathlessly intimate rendition of the solo leading up to Lucia's arrival. Anraku's harp remained subdued throughout, even quieting down to the most quiet of aural threads, bringing the audience into Lucia's frail and secret world.

Flautist Denis Bouriakov was just as wonderful accompanying Shagimuratova in the cadenza of the mad scene. He matched the quality of her singing beautifully, creating a dialogue between Lucia and some unknown presence, a figment of her imagination.

Mary Zimmerman's production is filled with fine gothic touches that allow the drama and music to unfold without major interruptions. Except in the second act when the arrangement of the hall for the wedding distracts from Lucia and Raimondo's duet. The same goes for the photograph during the sextet. The idea of playing with the words and the frozen action in the context of the photograph, art that literally freezes time, is surely well-intentioned but has a cartoonish execution. The photographers' consistent changes to the portrait add an irritatingly comic touch to a rather breathless musical moment.

However this does not take away from the brilliance of the central staircase used in the final act, a symbol that links Edgardo's descent into loneliness in his castle with Lucia's own descent into madness and eventually death. The decision to showcase the full moon as a backdrop to the final two scenes further connects the two lovers' deaths and adds an eerie quality.

Finally, the ghost remains a crucial and brilliant touch in the production. The spectre arrives during Lucia's opening aria, haunting her and the audience. It reappears at the start of the act, a reminder of the death dominating the world of the opera. And the ghost makes one final appearance in the final act, except that it is no longer the girl from Lucia's narrative, but Lucia herself haunting Edgardo and the audience in her final moment.

From a vocal perspective, this "Lucia di Lammermoor" is as good as it gets this season at the Met. Every singer brought finesse and true bel canto to every musical number. The production, despite some moments of continued annoyance, is among the most subtly brilliant at the Met in recent years and certainly worth a watch.