Mercy's chase - Jess Lourey

When agoraphobic genius Salem Wiley lands her dream job as an FBI cryptanalyst, she vows never to return to the witch hunt underworld, where ancient secrets encrypted by hunted women have the power to rewrite history. Her resolve disappears when sweet Mercy Mayfair, the child she is pledged to protect, is kidnapped. With the help of the enigmatic Agent Lucan Stone, Salem is forced to code hunt in Ireland, England, and Scotland to keep the girl alive. As the clock ticks, she must face the terrible truth that there is only one way to free Mercy: crack the unbreakable code of Stonehenge.