To say that Jessica Cornwell was born into the literary world is an understatement. Her aunt, uncle and maternal grandfather are all authors, her father is a screenwriter and her brother taught poetry at the University of California.

Oh, and her other grandfather is the acclaimed spy novelist John le Carre (real name David Cornwell), author of The Spy Who Came in From the Cold. Not that she felt compelled to follow suit.

"Originally my reaction to that was to very firmly believe that I could not be a writer," the 28-year-old says. "It was something that was very daunting in the context of coming from that family."

Raised in the small town of Ojai in southern California, Cornwell studied English at Stanford and gravitated toward film and theatre. She moved to Barcelona to undertake a graduate course in directing, taught primarily in Catalan. It stoked a fascination with the region which would later sow "the first major seed" of her debut novel, The Serpent Papers.

The thriller is the first in a medieval trilogy that garnered a six-figure publishing deal and, inevitably, comparisons to Dan Brown's The Da Vinci Code. It takes us into the universe of Anna Verco, an academic and book thief tasked with tracking down an ancient palimpsest, or re-used scroll. Her quest, set largely in Barcelona, becomes linked to the unsolved ritual murders of four women, and Verco finds herself increasingly at risk as her hunt for the manuscript narrows.

A lover of books and research, Cornwell has infused her heroine with some of her own qualities. But Verco is also a modern-day incarnation of a renaissance book hunter – manuscript detectives who discovered documents that "completely ruptured the Catholic hold of what literature was at that time".

"You have a really long history of people looking to books to find hidden histories or hidden meanings that have actually been obfuscated deliberately," Cornwell says. "Secret histories fascinate people because we are all aware that what we perceive is not necessarily how things are."

Cornwell's own interest in medieval mythology was stirred while working as an assistant director with experimental Catalan theatre company La Fura dels Baus, touring Shakespeare's Titus Andronicus. Cornwell became "completely fixated" with the character of Lavinia, who is raped and mutilated by two men. They sever her hands and cut out her tongue to prevent her from identifying her attackers.

"I really wanted to understand what Shakespeare was drawing from and what he was referencing," Cornwell says.

Living in London and working in film, she took a research trip to Majorca and began constructing an alternative history of ancient power and sexual violence towards women, based on the mythology behind Lavinia, the texts of 13th-century Majorcan philosopher Ramon Llull and the work of a number of Catalan alchemists.

Cornwell wrote the ambitious novel in six months and in July 2013 found an agent "overnight". The Serpent Papers is now being translated into eight languages, including Catalan and French, and she is working on the next part of the trilogy.

Cornwell's writing style is very different from her storied grandfather's – her third-person prose is laced with Verco's italicised thoughts – though their characters share an exposure to murky worlds of subterfuge and conspiracy. Le Carre is "an incredible man", she says, who has been an inspiration "not so much as an author but as a person".

They have talked about her novel but she has kept the manuscript closely guarded from her bookish family.

"I'll send him a copy now that it's coming out," she promises. "I think he's very proud. I'd hesitate to put words into his mouth but it's been a really nice extension of the relationship."

Now a full-time author, Cornwell may even turn her intricate pen to the subject of Australia. When she was 18 she lived for a month in the tiny Queensland town of Yungaburra, in the Atherton Tablelands outside Cairns. She had followed her then-boyfriend to his hometown, intending to pick fruit for a year.

"Needless to say, the romantic side of it didn't quite work out, but the experience itself was extremely rewarding," she says. "I would love to write about it some day."