Imogen Heap was involved in Harry Potter and the Cursed Child before she even knew the play existed. During the early days of the play’s top secret development, the movement director, Steven Hoggett, began experimenting with some of her pre-existing songs. For Hoggett, it seemed a natural pairing: “Her music feels magical,” he says.

A Grammy-winning solo artist who has also collaborated with everyone from deadmau5 to Taylor Swift, Heap ended up composing and producing hours of music for the epic production’s score. Now fans of both the musician and the boy magician can savor those tunes, thanks to the recently released album The Music of Harry Potter and the Cursed Child. Broadway Direct talked with Heap about the album and what it was like to work on the Broadway and West End smash.

Did you ever imagine that your music might be a good fit for the world of Harry Potter?

I had never thought so, but I was pleasantly surprised. Lots of these pieces I had written over the years more as passion projects. A lot of why it works has to do with the magic of how Steven has placed the songs in the play. Also, there’s something about Harry Potter that exists in its own world. It doesn’t connect to any real time or place, and a lot of people also say that about my music.

A lot of what ended up in the score is very clearly based on or inspired by some of your earlier songs.

We delved into 14, 15, 16 years’ worth of back catalog of my music. If I hadn’t had all these orchestral pieces and choral pieces that I’d written already, I’d never have been able to do it all. Fans might recognize a lot of it, but it’s been completely transposed, or it’s these tiny hints or snippets from the past. And there is a lot of new material in there as well. I really had to put my music theory to the test, because I had to bridge the gaps between the hundreds of tempos and keys in these quite separate pieces of music, and try to weave that into something that’s hopefully not completely confusing, but is quite nice to listen to.

The full, two-show experience of Harry Potter and the Cursed Child is divided into four acts. Similarly, your score is divided into four “suites.” How did you think about those suites and the different sounds required for each?

Suite One, we’re introducing the characters. It’s kind of up-tempo, and it’s really fast-paced, introducing you to different themes and feelings. Suite Two becomes a bit slower, a bit calmer. We’re going a bit deeper into the characters. Suite Three is where clearly something is up, something not good. Everything goes dark and heavy and electronic, with some drums and drones. And then Suite Four has got this more drawn-out feel, with this little tiny glimmer of hope right at the end. That’s actually the most uplifting piece, in terms of major key and tempo.

How is the experience of listening to the score different from experiencing it in the theatre with the full production?

I think the album has to bring you on its own journey, really. You don’t have the support of everything else that’s happening onstage. With the album, the challenge is to try to bring out that same kind of intensive experience that you have in the play, where you’re really in the moment. Although if you look at a song like “Welcome to Hogwarts,” that’s a minute or so on the album, but in the play it’s 10 minutes. I had to really try to amp everything up a bit and make sure the album is something you enjoy listening to.

A lot of times, the scene paired with your song — for instance, in the song “Platform 9 3/4” — matches the meaning of the original song that inspired it ,in this case, “First Train Home” from your album Ellipse. Was that intentional?

It’s funny: There’s this guy called Frankie Grande, and he’s a big fan of Harry Potter and also a big fan of me. He wrote this blog where he talks about all these subliminal texts that are going on in certain moments with the music. And I was like, “I wasn’t aware of that!” When I write a lyric, I hadn’t realized how much the music is also conveying the meaning of the song. There’s another example, in this song in Harry Potter called “The Blanket.” The original song is called “The Moment I Said It,” and it’s about saying something you wished you’d never said. In the show it’s used in the same kind of moment, where someone says something they regret. I wasn’t aware of that when I was choosing it for the play. I just thought: “I need something that sounds like that feeling.” So I learned about how I approach music through this play.

Scoring something like Harry Potter is a very different kind of work than what you do for your albums. Did you enjoy it?

Yes! What I love about it most is, when you’re working with other input, the kind of visual input you get when you put music together with a play, or with a film, it just kind of reaches out and tells you when something’s right. In the studio, you don’t have that confirmation. But when you have something visual, or some dialogue, or a light that comes onstage paired with the right music, you go, “Oh, that really works.” There’s a hidden dimension that reveals itself.

The Music of Harry Potter and the Cursed Child is out now from Sony Music Masterworks.