The Drain by Caitlin T. Vale

Poppy's got a boy problem. She stole some money from her arsehole ex and now he's after her, and he's not the forgiving type. When she runs into a sexy, mysterious woman known only as Cherie things get more complicated. Cherie says she can help Poppy out, but for a price. Cherie's looking for some people, and she needs a companion. The trip takes them across the country and into Europe. But Cherie isn't like anyone else. She's hungry. She can only travel at night. And the trail of blood she leaves behind her is only growing.