The border between worlds is closed. Natural disasters ravage both sides. And only one map can save them—if Sienna can find it before the shadow consumes her.

Sienna Farren never wanted to be a hero. She just wanted to cross back into the Borderlands to find Finn, the man she loves who's fighting with the Resistance against impossible odds.

But when Bridget sealed the border to stop a devastating plague, she trapped thousands on the wrong side—and triggered a cascade of natural disasters that threatens to destroy both worlds.

Earthquakes shatter cities. Tsunamis swallow islands whole. The balance between Earthside and the Borderlands is broken, and every day the catastrophes grow worse.

Sienna's only hope lies in her grandfather's journals and a cryptic reference to the Map of the Impossible—a legendary artifact said to navigate the space between worlds. But finding it means diving deeper into the magic that's already marking her skin with spreading tendrils of shadow. Each time she uses her Mapwalker abilities, the darkness spreads further. Soon, she won't be able to hide what's happening to her. Soon, she might become the very thing she's fighting against: a Shadow Cartographer.

In the Borderlands, Finn and his friend Titus race against time to find an antidote to a sinister drug that transforms pregnant women into vessels for mutant children. The Shadow Cartographers have weaponized fertility itself, creating an army of corrupted magic users while forcing desperate refugees into servitude. The woman Finn loves is on the other side of an impassable border, and every day that passes, more innocents suffer under the regime of his father, the Warlord Kosai.

As natural disasters escalate and the body count rises, Sienna must navigate the Ministry of Maps, ancient ruins, and her grandfather's cryptic clues to find the impossible. But some maps were hidden for a reason. Some paths were meant to stay closed. And some prices are too high to pay—even for love.

Perfect for Readers Who Love:

• V.E. Schwab's Shades of Magic series (parallel London worlds)
• Leigh Bardugo's Shadow and Bone (magic with a dark cost)
  
• Strong female protagonists navigating impossible choices
• Map-based magic systems and cartography
• Portal fantasy with high stakes and dark undertones
• Separated lovers fighting to reunite across worlds
• Magic that corrupts the user over time

Series Information: Map of the Impossible is Book 3 of the Mapwalker series. While each book builds on the previous story, the series follows Sienna's journey deeper into the magic and mysteries of the Borderlands. Best read in order for full emotional impact.

Map of the Impossible completes Sienna's character arc, so this is a complete fantasy trilogy.

Previous Books:

• Book 1: Map of Shadows
• Book 2: Map of Plagues
• Book 3: Map of the Impossible

Themes & Setting: Set between contemporary Bath, England and the fantastical Borderlands, this book explores the cost of magic, the weight of duty versus desire, and the consequences of sealing borders between worlds. Atmospheric and immersive, with vivid descriptions of parallel dimensions, ancient maps, and the Ministry of Maps—a secret society of magical cartographers.

Story Details:

• Genre: Portal fantasy, speculative fiction, dark fantasy, adventure
• Length: Full-length novel (approximately 70,000 words)
• Reading time: 6-8 hours
• Mood: Dark, atmospheric, urgent, romantic tension
• Setting: Bath (England), the Borderlands (parallel world)
• Content note: Contains violence, natural disaster scenes, themes of forced reproduction, and dark fantasy elements. The shadow magic system has corrupting effects on users.

The border is closed. The worlds are dying. And Sienna Farren must find the impossible—or lose everything.