City Infernal (City Infernal, #1)

Hell is a city. Forget the old-fashioned sulphurous pit you may have read about. Over the millennia, Hell has evolved into a bustling metropolis with looming skyscrapers, crowded streets, systemized evil, and atrocity as the status quo.

Cassie thought she knew all about Hell. But when her twin sister, Lissa, committed suicide, Cassie found that she was able to travel to the real thing—the city itself. Now, even though she's still alive, Cassie is heading straight to Hell to find Lissa. And the sights she sees as she walks among the damned will never be in any tourist guidebook.