The weight of souls

"Sixteen year-old Taylor Oh is cursed: if she is touched by the ghost of a murder victim then they pass a mark beneath her skin. She has three weeks to find their murderer and pass the mark to them - letting justice take place and sending them into the Darkness. And if she doesn't make it in time? The Darkness will come for her ... She spends her life trying to avoid ghosts, make it through school where she's bullied by popular Justin and his cronies, keep her one remaining friend, and persuade her father that this is real and that she's not going crazy"--Publisher's description.