Para-archaeologist Lydia Smith has spent her entire adult life digging into the past, and building a career. But all that changes when she finds herself lost in the catacombs below the city, with no memory of how she came to be there. Now it's her own past that is eluding her; and the secret of what happened to her will endanger everything she's worked to rebuild, including her new marriage to Emmett London, who has a dangerous past of his own to overcome.