Not only has success not gone to Isaac Brock’s head, it apparently hasn’t even hit the Modest Mouse frontman yet.

Isaac Brock doesn't sound like a guy whose record entered the Billboard album chart at No. 1 the week of its release. Reached at his Portland home, the Modest Mouse frontman is, if anything, somewhat puzzled.

"When the record first came out, I didn't feel any glee or any real relief or anything," says Brock, audibly smoking. "And I thought that was kind of odd. Then when someone called and told me that it debuted at No. 1, I felt kind of weird because I felt like I was supposed to be excited and I didn't feel anything. Then I got kind of Eeyore-ish, like 'God, am I just not satisfied with anything?'"

Few people who caught the band's occasionally chaotic but often mesmerizing early performances could have predicted this kind of success for the abrasively off-kilter act. Though its 1997 record The Lonesome Crowded West spread the word beyond its Pacific Northwest roots, Modest Mouse still seemed an acquired taste–one requiring a tolerance for Brock's barking, yelping, declarative singing, and the group's serrated guitar licks. Yet in 2004, Modest Mouse's second Epic release Good News for People Who Like Bad News–buoyed by the single "Float On"–became a hit. After selling nearly 1.5 million copies of that album, the band is now one of the few post-grunge rock acts capable of climbing past former American Idol contestants (two of whom are also currently stationed in the top 10) on the charts.

Which brings us to We Were Dead Before the Ship Even Sank. Like the previous record, it was made with producer Dennis Herring in Oxford, Mississippi. Unlike with that album, there were no mental breakdowns during its making. (Drummer Jeremiah Green left Modest Mouse during Good News and ended up, briefly, in a psychiatric hospital; he's back now.) Another difference is the addition of Johnny Marr, an alt-rock star in his own right due to his time in the hugely influential British band the Smiths.

Marr's presence is put forward forcefully in tracks like the first single, "Dashboard", in which he and Brock play off each other, their guitars sparking like a bumper grinding against a guard rail. That kind of tension has always been a crucial part of the Modest Mouse mystique. But pop hooks leaven the group's more abrasive aspects, and it's not uncommon for songs to shift mood–"Florida" starts in attack mode before leading into a soaring chorus that's aided by backup vocals from the Shins' James Mercer. And "Spitting Venom" begins as furiously as its title implies, but halfway through slips into a bittersweet farewell.

In combining the quirky with the accessible, not to mention its herky-jerky rhythms, Modest Mouse is clearly indebted to the Talking Heads. The lyrics share some of the sensibility of Heads' frontman David Byrne as well–"Carbon", for instance, asks the listener to consider something commonplace until it seems strange.

"On this record, I really just dug in with the people I was working with," says Brock. "In the past I think I looked to my influences a lot more than I did on this one, except in books." He does admit to being a huge Talking Heads fan, though, particularly of the group's second album, More Songs About Buildings and Food. "The guitar playing on those early records was fucking out-of-hand cool. I really got lost in it at times."

Asked to name a book that may have affected his words for the record, Brock mentions You Can't Win by Jack Black. Published in 1912, the book tells of the author's life as a career criminal, but "one with integrity", says the singer. "He ended up in jail quite a few times. At one point he's talking about being in a Canadian prison. He found that, because they weren't able to talk to other prisoners, it created a more peaceful environment. There were no stool pigeons or anyone selling anyone out, and no opportunity for personal conflicts. He really enjoyed it. It was–I hate words like this–meditative."

For the 31-year-old musician, whose own scrapes with the law have been well-documented, the book must have hit home to some extent. But after learning his lessons the hard way, Brock is more at peace these days, even when it comes to his own motives for making music.

"I was talking to Dennis Herring the other day, and it finally hit me," he says. "The moments where I felt really great–like the way I think a lot of people would feel if their record went to No. 1–was usually”¦if we felt like we'd really accomplished something, like something really neat had happened. That was kind of a relief for me to realize–the part of making music that gives me that fucking No. 1–record feeling is just working on the project. It felt good because I kind of believed it was true but you never know whether maybe, somewhere in the deep recesses of your mind, there's an ulterior motive maybe you're not even letting yourself in on. But I got the message loud and clear–the reason this [the No. 1 record] doesn't matter to me is because I just like making the music. I'm not concerned about that shit. I'm not just talking out of my ass when I say that. It's true."

Modest Mouse plays the PNE Forum on Monday (April 16).