Nick and Amy Renee Heidemann-Noonan of Karmin have some theories about “Stranger Things.”

“The whole next season is going to be about finding Eleven again,” says Nick. “It’ll have something to do with that snake-like creature they planted inside of those people. It’s harvesting. Will already threw up that bug.”

The Berklee grads binge-watched the season while preparing for their upcoming tour in support of their sophomore studio album, “Leo Rising,” due out Sept. 9. The follow-up is a punchier, brash departure from their sweet, soulful pop 2012 debut, “Hello,” following the signs of the zodiac to inspire each of 12 tracks. The couple — who are both professionally and romantically intertwined — call from Los Angeles, their new home, where they’re in the midst of moving in and renovating.

How did the inspiration to do a zodiac-themed concept album come about?
Amy: We have a strange story about this. About two years ago, on our birthdays, the band and the crew gifted us a meeting with an astrologer. At first we were like ‘Uh, this is interesting…’ but we thought we should go and humor them. It turned out to be a meaningful event for us. The astrologer put us in touch with a spiritual side and gave us perspective as to what we’re doing with our lives. We decided after that to leave our major label, and as the album took shape, each song became a persona.

One thing to note — the album has 13 tracks, but there are only 12 zodiac signs. What’s the straggler?
Nick: Well there’s a secret 13th sign [laughs] No, the album is 12 songs, with a bonus track.
Amy: The bonus track is one that’s inspired by political and global events.
Nick: The global s—t that’s happening now. We’re reaching a point now [as a band] where we’re a growing community and we can comment on those things.

Each song is correlated to a different zodiac sign — so what came first, the characters or the music?
Amy: They started as characters. I like to write lyrics like it’s coming from someone else — you have to get out of your own head.
Nick: We tried to take characteristics [from each of the signs] and represent them in the lyrics. Like, Cancer is focused on home and family, so [“No Suitcase”] is a song about a person who is trying to find those things. They feel like they don't fit in. Sagittarius is fun-loving but they can also be a heartbreaker so you get a song like “Blame It On My Heart.”
Amy: The most direct is the Aries track [“Dance With You”], it’s an aggressive warrior-like song.

Did you ever feel trapped in the idea of a “concept album” once you started writing it?
Nick: The idea didn’t start to make sense until two or three songs in. “Sugar” and “Don’t Know You” — we were like, “Oh, that sounds like a Gemini song…” because it bounces back and forth like dual personalities.
Amy: It was organic like that.
Nick: Then “Sugar” is a fun, artsy, upright jazz thing and Taurus rules art.
Amy: And Taurus is materialistic, like “Sugar”…
Nick: Exactly.

One of the songs is a cover of “Pure Imagination” from “Willy Wonka” — which, with the timing of Gene Wilder’s passing, is both sad and poignant.
Nick: That was one of Amy’s favorite childhood movies.
Amy: He was such an inspiration — all of his work is incredible. When he sings that song, it’s so timeless and unforgettable. We were so thankful we were able to get permission to put it out and add our own verses.

You guys usually keep quiet about your personal lives, but am I right in saying a big milestone for you this year was getting married?
Amy: We’re married, and we’re loving it. Though it doesn’t feel all that different now.

Given your working and personal lives collide, do you find that puts your relationship on the table all the time?
Nick: Pretty much.
Amy: But we don’t mind it either. We’re like, “Whatever.”

Do you think getting married had any effect on the outcome of this album?
Amy: Nick produced the whole album, and the fact that we’re together all the time is a really interesting way to create. We’re very open and honest with each other.