"Thick stoner-metal sludge and peat-bogged prog-folk arpeggios."

"There's child murder, a jealous queen and enough anachronism to power an autogyro or gramophone for weeks."

"Drowns in convoluted plots, blustery guest vocalists and comically out-of-place guitar shredding."

So read the reviews of the Decemberists' new album, "The Hazards of Love." And half of those were favorable, too.

After four previous records that already demanded a lot from fans -- including heavy use of a dictionary and a Cliffs Notes guide to seafaring legends -- the Portland, Ore.-based folk-rock ensemble really cast a long net with its latest disc, an hourlong, character-driven, 17-part rock opera. It features heroines and villains and revenge and, of course, love, plus a lot of amped-up guitar work that recasts the Decemberists as a metal band. Comparisons to Spinal Tap have been commonplace. At the same time, many of the band's fans and adventure/kitsch-seeking music lovers have been drawn into the disc's ambition and eccentricities.

The Decemberists will play "The Hazards of Love" in its entirety at Saturday's Rock the Garden concert, as they're doing all summer. Two indie-rock songstresses who provided guest vocals on the album are along for the tour, too: Shara Worden, aka My Brightest Diamond, and Lavender Diamond's singer, Becky Stark.

Colin Meloy, the group's newly sideburned frontman, good-naturedly defended and explained this quizzical turn for his band recently by phone from a tour stop in Atlanta.

Q First the Decemberists, and now Green Day. Is this the year rock operas or concept records become cool again -- or for the first time?

A To be honest, I sort of just have a passing interest in concept records. I think it's an interesting form. Hüsker Dü's "Zen Arcade" would be my most important concept record if I had to make a top five. But I'm also into '70s Broadway musicals such as "Evita," "Hair," "Godspell" and "Jesus Christ Superstar." I listened to those a lot when I was a kid, because my whole family was into theater and Broadway. So there's always been a part of me that has loved the idea of a record telling a story from start to finish.

Q The disc has earned a decidedly mixed reaction. Did you expect that to be the case?

A I figured it would be pretty polarizing. But it came at a time when I was a little frustrated with expectations to create radio singles and a tidy 50-minute record with 10 songs and a couple radio singles and ballads. It felt like the perfect time to just follow my creative whim. I think, of any of our records, this is the one where I followed my whim most closely.

Q It's not just the concept that's been polarizing, but the musical change-ups -- namely the album's heavy-metal flavor. Where did that come from?

A I think it grew out of this interesting connection that I see between old folk music and metal. ... There's a common love for mythology and folk tales. It was fun to explore that connection. Lyrically, all the sort of dark elements on the record -- murder, rape, violence -- pop up in our other records, too, so that's not entirely something new [laughs]. I was drawing almost entirely from elements of old folk songs. These songs were written in a very different era when the world was quite a bit dangerous than it is today.

Q As serious as this all sounds, is there a side to this record that's tongue-in-cheek and more just for fun?

A Oh, of course. It kills it a little bit to say that. We're all real street record collectors and love mining these different genres and different eras of music. It's really fun to bring these things to present and do them in a sort of playful way.

Our whole body of work has been a number of records being playful, jumping around from genre to genre and involving certain songwriting styles that, in context, are sort of ludicrous. We like pasting this sort of high-minded mentality over pop songs. It's all sort of a wink a nod to marginalized people of the world, which are my stock. I think of my records as secret-coded messages to marginalized people, telling them they are not alone.

Q Let's face it, though, most people can't follow the record's story line. Can you?

A I think that's a tradition in most concept records. In order to do it right, we had to make it abstract. A certain amount of the burden is put on the listener to tie up some ends and put the pieces together. That's half the fun of a concept record. You have to take a bit of a logical leap. The concept record grew out of the psychedelic movement, and that was all about a Dada-esque approach to music and creating willful abstractions and letting the audience's imagination create a story.

Q OK, so is there a moral to the album, or a point?

A Oh, I don't know [long pause]. The record is all about archetypes. So one thing you can learn is: If you try to cross a river that you made a deal with, it will drown you on the way home. Let's call that the lesson.

Chris Riemenschneider • 612-673-4658