Blood, Sweat and Demon Tears: The Grateful Undead series

Susan's sister is in one hell of a mess (literally); confined to servitude with the demon, Rafael. When Rafael gifts JoAnn with an Earth-to-Abyss cellphone so she can communicate with her sister, Susan soon finds out that JoAnn has gone from servitude to concubine, and no longer wishes to come home. JoAnn really loves her new Hell phone. Problem is, the frequent calls home--time really moves like Hell in the Abyss--are putting a large dent and Susan and Marcus's bedroom time. In their attempt to retrieve JoAnn, THE GRATEFUL UNDEAD team ultimately find themselves knee-deep in vamp critters, demons, rogues, and a host of new and colorful characters, when the mission takes them from their home in Florida to the streets of New Orleans.