Lullaby by Claire Seeber

Jess, her husband, Mickey, and their eight-month-old son, Louis, spend a long-overdue day together at the Tate Museum in London. After lunch, Jess gets separated from them and is overwrought to discover that they've disappeared. Mickey is soon found, badly beaten, but Louis is still missing. Who would have taken him? Is it someone who knew the Finnegans or a stranger who saw an opportunity? From Jess' unsavory brother to the family's French nanny, there's no shortage of who could be responsible. Lullaby explores Jess' search (with the police's help) to find her son, along with the backstory of Jess and Mickey's far from perfect relationship.