False hearts
(Book)

One night Tila stumbles home, terrified and covered in blood. She's arrested for murder, the first by a civilian in decades. The San Francisco police suspect involvement with Verve, a powerful drug, and offer her twin sister Taema a chilling deal. Taema must assume Tila's identity and gather information -- then if she brings down the drug syndicate, the police may let her sister live. But Taema's investigation raises ghosts from the twins' past. The sisters were raised by a cult which banned modern medicine. But as conjoined twins, they needed surgery to divide their shared heart--and escaped. Taema now finds that Tila discovered the links between the cult and the city's underground. Once unable to keep secrets, the sisters will discover the true cost of lies.--,from author's website.