Many people think opera is one of those art forms that only aficionados understand and only the experts can really enjoy.

With “The Tales of Hoffmann,” even novices to opera can take comfort that connoisseurs won’t know much more than they do — because presentations of the opera take so many shapes and sizes that, beyond the broad outline of the story, it’s impossible to know what’s coming.

“The great thing, and always the challenging thing with this opera, is that there is no definitive version,” said tenor and guest artist Eric Fennell, who plays the title role in Hawaii Opera Theatre’s production of Jacques Offenbach’s 1881 masterpiece. “Musically, there are different numbers that can be put in and taken out. … Some of the scenes and arias for the sopranos exist in different keys. It’s all allowed because Offenbach wrote it that way.”

“It’s classic and traditional at the same time, fantastic and realistic at the same time,” said Henry Akina, who is directing his final work for HOT. “We have a great cast.”

THE OPERA is a takeoff on the life of E.T.A. Hoffmann, an author, poet, musician, lawyer and judge during the stormy Napoleonic era. Three of his short stories were adapted into a play in 1851, with the playwrights employing Hoffmann as the main protagonist (a ploy used in the 2016 film “Nocturnal Animals”).

Offenbach based his “opera fantastique” on the play, composing a huge work that has 24 named characters. Among them are a robotlike doll, Olympia, one of Hoffmann’s love interests, played by Rachele Gilmore; the Four Villains who antagonize Hoffmann, played by Wayne Tigges; and Hoffman’s sidekick Nicklausse, a “pants role” — a youthful male role traditionally portrayed by a female singer — played by Olivia Vote. To complicate matters further, Vote opens the opera as The Muse, a female who introduces the story before transforming into a youth.

Hoffmann is first portrayed during a down-and-out period in life, after he was deposed from his jurist post and resorted to telling stories in taverns to earn money so he could drink. His opening scene features the comical aria, “The Legend of Kleinzach,” and then flashes back into stories about his terrible love life: a foolishly superficial attraction for Olympia; a sincere but tragic relationship with music-loving Antonia (Christine Arand); and a spiteful, lust-driven liaison with courtesan Giuletta (Eve Gigliotti).

“The stories are all fantastical,” said Fennell, who has portrayed Hoffmann in four other productions. “He falls in love with a robot? A woman who sings herself to death? There are no limits in this opera.”

Vote, who is performing as The Muse/Nicklausse for the first time, finds her role liberating. As the Muse, she adopts an “ethereal, godlike” presence, she said, whereas as the youth Nicklausse she can be more physically aggressive.

“The joy of playing a pants role is that you don’t have to apologize,” she said. “Men, they just go for what they want. As a woman, you’re oftentimes saying, ‘Maybe he likes me or he doesn’t like me.’”

Nicklausse sometimes eggs Hoffman on and at other times warns him of danger, whether the advice is wanted or not. “I think Nicklausse thinks he’s the best friend, and Hoffman is like, ‘Who is this person following me around?’” Vote said.

Tigges gets to play “the bad guy in every act,” he said: Lindorf, a romantic rival; Coppelius, who exposes Olympia as a doll and Hoffman as a fool; magician Miracle, who causes the demise of Hoffman’s one true love; and manipulative Dapurtutto.

Tigges drew inspiration from different Hollywood characters for the roles: Vincent Price’s “classic villain — suave but definitely menacing”; a Robin Williams-like persona; the dramatic presentation of magician David Copperfield; and Clint Eastwood’s swaggering presence.

Musically, “Hoffmann” has been evolving over the years, said conductor Vincent de Kort. Offenbach died before completing the opera; his students contributed to the final work, but historical editions of the score have revealed overlooked details. The opening “Glug-glug” song, for example, which refers to drinking and is traditionally performed in a straightforward rhythm, actually has a syncopated beat that more accurately conveys drunken revelry, de Kort said.

“What we’re doing is much more funky stuff,” de Kort said. “Here it’s French style and it’s a very specific style, which is not easy, but it’s light and it has sharp accents and has offbeat moments, so it becomes a light, lively show. And with all these characters, it will be sort of a whirlwind.”

THERE ARE many great arias in “Hoffmann,” but the unquestioned showpiece is Olympia’s “Les oiseaux dans la charmille” (“The birds in the arbor”), known as the Doll Song. It gave Gilmore her breakout moment in 2009, when she was a last-minute replacement at New York’s Metropolitan Opera. As is customary, she incorporated her own ornaments into the song, reaching a stratospheric A-flat above high C, which had some observers wondering whether it was the highest note ever sung at the Met.

Gilmore is blessed with a natural ability to sing at high pitch and doesn’t even consider the Doll Song to be one of the more difficult arias. Nonetheless, she notes, “It’s challenging because you come out and you just have to go right away. You don’t have anything to warm up with.”

She also has to move like a doll. “You’re having to keep your body very stiff, and sometimes because of that your breathing can get a little bit stiff,” Gilmore said. “We always want to keep our bodies sort of pliable. I definitely have to remind myself to relax.”

Operagoers, whether expert or not, should also relax and enjoy the show.