The Decemberists show Friday night at the Byham will bear little resemblance to the last time the band played here, in 2003.

Back then, the Portland indie-rockers had just released their second record, "Her Majesty the Decemberists," on the indie label, Kill Rock Stars.

"I think we've just become more confident as a band. The more you work at it and the longer you stay with it, you progress one way or another, for better or worse," says guitarist and multi-instrumentalist Chris Funk. "We're all game to take chances. I think we've become better musicians, too, and more complete in how we make records and how sonically we sound."

The obvious difference is how expansive the Decemberists have become, culminating in the band's latest project, a full-blown rock opera called "The Hazards of Love." On the current tour, the band is performing the 17-track piece in its entirety before returning to the stage with a set of favorites from the back catalog.

The genesis of the project -- and Genesis is an appropriate word, considering the progressive-rock indulgence -- was singer-songwriter Colin Meloy being approached by the producers of "Spring Awakening" to write a rock musical.

"It started as a bona fide musical," Funk says, "and then the producers and he decided that it didn't have legs for a complete musical, so Colin was so deep into it and we all dug the music, we're like, 'We should put it out this way.' All the while it was going to be a Decemberists record. It was more borne out of the format of the stage."

In a nutshell, "Hazards" is a surreal fantasy centered around a woman who ventures into the woods in search of the shape-shifting forest beast who impregnated her, encountering an angry jealous forest queen and a kidnapping rake who has murdered his three children.

Musically, it calls upon the full arsenal of the Decemberists' talents, not to mention the band's instruments. It shape-shifts from British folk to ambient rock to heavily distorted metal.

"I think 'Hazards of Love' is very much like a fantasy for us to be in," Funk says. "It's kind of the Decemberists, and kind of not the Decemberists -- we don't play guitars like that all the time. So under the guise of some fictitious musical, it gave us more freedom to assume other musical characters, if you will, in the studio, arrangement-wise and electric guitar-wise.

"I don't even think of myself as an electric guitar player," he adds. "I'm more interested in acoustic instruments, in folk instruments. But playing electric guitar is the best thing in the world, the most indulgent half-hour you ever have -- visceral, aggressive, another genre of music."

Funk says he and Meloy both have roots in musical theater. He grew up with his mom taking him into Chicago to see musicals and went on to play in pit orchestras. Of course, an affection for classic-rock concept albums fits in there as well.

"We're big fans of the Kinks, who made tons of concept records, and Pink Floyd and The Who. Our drummer always jokes that we're kind of like a classic rock band. But I think he's right. I look at what people listen to in the band. People do listen to Steve Miller and Pink Floyd and all that stuff you're not supposed to like and then be involved in indie-rock. But I think people's palettes have expanded in general, and that's a good thing."

To pull off the characters in "Hazards," the Decemberists will be augmented by two singers: Shara Worden of My Brightest Diamond and Becky Stark of Lavender Diamond. Funk says the band went for a souped-up light show, but chose to avoid other theatrical elements.

"We had talked about doing some kind of film or animation, then we just settled on a light show. We wanted to keep the focus on the music. We could have gone crazy with this, drop puppets from the sky like Pink Floyd or something. We didn't want to go full tilt."

While working on "Hazards," Funk says the band has developed a wealth of new, unrecorded material and expects the next Decemberists' record to be a return to knocking out Meloy's songs on acoustic guitars.

"We're not like a singles-driven band, though we're on a label, Capitol, that I assume would like us to behave like Coldplay or something and deliver a single that's going to smash us over the top. We don't have those kind of pressures. We just plod along and do what we want."

Now that he brought it up, does Funk foresee the possibility of the Decemberists breaking through as that type of band?

"Yeah, we write three-minute-long songs and we explore the pop format, so anything's possible. I look at like Kings of Leon, which has been a band for a long time and this year exploded. It just takes one song."