It was a Thursday night in a massive rehearsal hall in Indiana University's Musical Arts Center, and Carolina Castells didn't look so good.

But that was as it should be. The soprano from Miami was rehearsing a scene from the second act of IU Opera Theater's production of the comic fantasy "Tales of Hoffmann."

Castells' character, Antonia, one of three loves being fondly recalled by poet E.T.A. Hoffmann, is a typically tragic opera character. Antonia is a consumptive singer who has been strictly warned that she will die if she dares to sing. And she ignores that advice.

Following Antonia's soon-to-be-fatal error in judgment that night in the MAC, Castells did her very best to look sickly. But apparently not sickly enough.

"All of those collapses are not strong enough, Carolina," said Chris Alexander, the production's guest stage director. "They have to be strong, because right now, I don't see the illness."

It's a wonder that Castells, a 25-year-old graduate student, didn't look more under the weather. After all, she was facing midterm exams and had performed in New York City only a few days earlier.

But Castells didn't seem fazed.

"These rehearsals, well, they are all about juggling everything all at once," she said. "I have to write everything down. But this opera is actually easier for us, the three women, because we are only in one act each."

While in New York, Castells sang on the stage of the Metropolitan Opera. She won that honor as one of nine finalists in the Met's 2008 National Council auditions. The council's purpose is to discover new talent and encourage young singers with career preparation.

"With the grand finals," Castells said, "it was mostly just the nerves of singing on the Met stage with the Met orchestra. It was just a bigger experience. But as one of the nine finalists at that point, it was understood that everyone was excellent and that you had worked really hard to get there."

Castells, who has a bachelor's degree from the University of Miami, is accustomed to putting in long hours.

She works a part-time job for Indiana University's Jacobs School of Music. She has performed in several IU Opera Theater productions. She also has sung with the Indianapolis Symphony Orchestra and performed the Brahms "Requiem" in Bloomington and Indianapolis.

This semester, Castells hopes to finish her master's degree (in vocal performance). And not unlike many music school students completing their academic careers, she is not exactly sure what's next.

But again, she seems unfazed.

"Well, I might stay here another year just to work with my teacher," she said. "Things are pretty much up in the air."