Europa Series by Joseph Robert Lewis

In the exotic land of Marrakesh, Omar Bakhoum joins an airship expedition into the freezing north in search of a fabled country called Ysland, but howling ice storms, legions of ghosts, and a deadly samurai stand between Omar and his goal. His journey has barely begun before the members of the expedition team begin dying, and as the last remaining foreigner on board, Omar is accused of the murders... moreIn the exotic land of Marrakesh, Omar Bakhoum joins an airship expedition into the freezing north in search of a fabled country called Ysland, but howling ice storms, legions of ghosts, and a deadly samurai stand between Omar and his goal. His journey has barely begun before the members of the expedition team begin dying, and as the last remaining foreigner on board, Omar is accused of the murders. The one thing that can help him find the real killer is Omar's ancient sword, haunted by the souls of thousands of dead sages and warriors. But this sword may be the very thing that dooms the entire expedition to a watery grave. less

Last night, Freya's sister was bitten by a horrific beast in the snowy hills of Ysland. Now, Freya has only a few hours to find a cure for this strange plague before her sister becomes a ravening fox demon. With her husband Erik and the young witch Wren at her side, Freya discovers that the blood-thirsty monsters have already ravaged her homeland as she explores deserted cities full of ghosts and meets a few lonely survivors on the edge of madness... moreLast night, Freya's sister was bitten by a horrific beast in the snowy hills of Ysland. Now, Freya has only a few hours to find a cure for this strange plague before her sister becomes a ravening fox demon. With her husband Erik and the young witch Wren at her side, Freya discovers that the blood-thirsty monsters have already ravaged her homeland as she explores deserted cities full of ghosts and meets a few lonely survivors on the edge of madness. She finally seeks answers in the ancient city of Rekavik where she must face the deadly witch queen Skadi and the vicious warrior Leif Blackmane. But the only person who can cure the demon plague is the same person who created it, a stranger from a distant land who carried a sword full of captured souls, a man who was murdered five years ago... But not even death will stop Freya from saving the people she loves. less

Wren has followed the mysterious Omar Bakhoum from her home in Ysland across the frozen wastes of Europa to the warring cities of Constantia and Stamballa, where war is the least of Wren's problems. On steam-driven ironclads she meets more of Omar's immortal brethren who have all but lost their humanity, and in the icy streets she finds a legion of frozen corpses waging a war of their own against the living... moreWren has followed the mysterious Omar Bakhoum from her home in Ysland across the frozen wastes of Europa to the warring cities of Constantia and Stamballa, where war is the least of Wren's problems. On steam-driven ironclads she meets more of Omar's immortal brethren who have all but lost their humanity, and in the icy streets she finds a legion of frozen corpses waging a war of their own against the living. While Omar leads the fight against the undead, Wren sets out alone to pit her wits and skills against the most powerful witch in the world, the immortal Rus crone Baba Yaga, who has gone mad with grief from the loss of her son, Koschei the Deathless. A cruel gauntlet awaits Wren as she confronts the spiteful souls of her dead teachers, her own secret fears made flesh, and the waking nightmares of Yaga herself. It's not all doom and gloom, though. A handsome young major in the Constantian army has caught Wren's eye, and Omar has taught her a few new tricks, like how to control the aether mists that reveal the souls of the dead. And if she can defeat the other-worldly forces besieging the city, the only thing left in her path will be a vast armada of naval destroyers and deadly airships. But that's all right. Wren likes a challenge. less