"It's a punctuation joke," Jenny Hollingworth says. She's explaining the name of her band, Let's Eat Grandma, over Skype. "If you have ‘Let's eat, Grandma,’ it's like, ‘Come, Grandma, let's go have dinner.’ But if you take the comma out..."

"Then it's not such a nice dinner anymore, is it?" says Rosa Walton, the duo's other member.

"Well, it is for you," Hollingworth says, laughing. "But not for your grandma."

The 17-year-old girls of Let's Eat Grandma, a rising band from Norwich, England, certainly like a good macabre joke. In press photos and live performance videos, the duo look like minor characters in a Gothic horror film, playing off of their similar doll-like features, long light-brown hair, and high-pitched voices to create an eerie twin-sister vibe. Their debut album, I, Gemini, is full of freaky, slightly-off indie pop sounds reminiscent of CocoRosie's early records, weaving together stories of Rapunzel and chimpanzees swinging in forests. It's an album full of clamoring and unexpected textures, all strumming mandolins, froggy saxophone solos, and pan flute harmonies.

Let's Eat Grandma grew out of Hollingworth and Walton's everyday extracurriculars as kids, which included treehouse-building and making "spy movies" about sneaking a peek at their neighbors. "When you're a kid, you sort of experiment with things," Walton says. "We didn't really think, Oh, this is the start of our career! We just thought we'd do a few covers or something." The two initially wrote their songs with live performances in mind, with a heavy emphasis on choreography, and had no intention of recording an album until a small U.K. label called Hand of Glory reached out about a deal after seeing them play.

"They found us and we were like, yeah, cool," Walton says dryly about the deal. "Then we went and had a nice dinner."

"It was a very nice dinner, actually!" says Hollingworth. "I had some pea soup."

A little messy, and often more silly than creepy, I, Gemini plays like a record of demented children's music. "I've got a foot in my mouth, I've got a tongue in my feet," the two sing on a song called "Chocolate Sludge Cake." On another, "Sleep Song," they try to figure out what to do with the voices in their heads. "I Googled it, but not even Google understands," they wail over warped accordions. Walton and Hollingworth wrote most of these songs when they were just 13, which explains some of the childlike irreverence of both their lyrics and music. "That's where we were at that point in our lives," Walton says. The two are eager to not just release new music, but to see what everyone else thinks of it. "The best thing would be comparing the response to the [current] album to our next release," Hollingworth says. "Sometimes it's hard to analyze your development, and then people just do it for you online, so that's a job saved!"

Not that people haven't been quick to analyze their development as young women already. "When we first started, I don't think people really respected us, whether it was the other bands at a gig or the sound engineer looking down on us," Hollingworth says. "I think you have to work a bit harder to get the same amount of respect from people," Walton says. "It's kind of annoying." The spooky-sibling freakshow bit is a way for both of them to dig their heels into perceptions of girls. "We're playing with people's expectations," Hollingworth says. "People often expect when they see us, because we're young girls, that we might be a bit more docile. They have this preconceived notion of what we're going to be like, and we like to challenge that."

Listening to I, Gemini, I was reminded of the Cottingley Fairies photographs, in which two girls faked evidence of real-life fairies in the early 20th century. They drew a far more mature public into a magical little universe of their own making, even though it turned out to be a hoax, and made adults think seriously for a second about the storytelling and imagination of young girls. I, Gemini is a promising debut because it feels like that same sort of peek into a tiny girl-world universe where, if magic doesn't present itself, you make it yourself. It's music by teenage girls devoid of real-world objectification, of love songs and sex; its drama seems to come from the stir-crazy feeling of being home on a weeknight starting at a textbook. In the end, Let's Eat Grandma seem to be less freakish outsider-artists than normal girls who are far better attuned to a world adults have long forgotten how to access.