Holly Jackson is entering a new era.

PEOPLE has an exclusive first look at the cover for the A Good Girl’s Guide to Murder author’s new book, Not Quite Dead Yet. The novel, forthcoming from Bantam this summer, marks the writer’s first foray into adult fiction.

In Not Quite Dead Yet, Jet, the 27-year-old daughter of a wealthy Vermont-based family, is still figuring out her next steps. Her world is rocked, however, when she’s brutally attacked by an unseen assailant on Halloween night. Jet suffers a head injury, which her doctor says will lead to a deadly aneurysm within a week.

The incident leads Jet to consider both her mortality and who she can trust. Everyone in her life becomes a suspect in the attack, from her family, to her former best friend and her ex-boyfriend. As the clock ticks down to her death, Jet must figure out who has it out for her, before it’s too late.

The author tells PEOPLE that her latest book is particularly special to her.

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“I’m so excited for this one — I think it’s the best thing I’ve written yet,” Jackson says. “And although this is something new for me — branching out into the adult market — I am sure my existing readers will feel right at home in Not Quite Dead Yet, with all my signature thrills and unhinged twists.”

Jackson made her mark in the young adult genre with her breakthrough thriller, 2019’s A Good Girl’s Guide to Murder. A BookTok sensation, the novel garnered even more attention when it was turned into a Netflix show, starring Wednesday’s Emma Myers, in 2024.

Jackson returned to the series with the book’s sequel, Good Girl, Bad Blood, prequel novella Kill Joy and riveting finale As Good As Dead. The author’s standalone novels include Five Survive and The Reappearance of Rachel Price.

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Jackson’s latest brings her familiar thrills to a new audience, as she steps into the adult realm.

“Jet has just seven days to solve her own murder, and readers will only have 400 pages to do so,” the author says. “Let the countdown begin.”

Not Quite Dead Yet will be published on July 22 and is now available for preorder, wherever books are sold.