10-year-old Harper wowed the America's Got Talent judges with her performance of Spiritbox's "Holy Roller." Check out the clip below.

Coincidentally, the episode aired the same night Harper was invited to perform the song with the band.

Read more: 20 best stripped-down songs, from Spiritbox to Silverstein

Harper walked onstage, drawing comments about her cuteness from the judges. Shortly after, their faces twisted in shock as she began to sing.

Simon Cowell remarked, "Have you ever seen a film called The Exorcist? Actually, kidding aside, that was brilliant. I mean, brilliant. It was like a mouse turning into a vampire bat or something."

All three judges gave Harper a "Yes," securing her position in the next round.

Harper also joined Spiritbox onstage at O2 Academy in London to reprise her performance alongside Courtney LaPlante.

Watch Harper on America's Got Talent and her performance with Spiritbox below.