Prey by Hilary Norman

In 1941, Harriet lives at Calla House in northwest London. She owns the building and inhabits the top floor, renting out the bottom floors to people who have become her friends. However, a killer is afoot, murdering women with red hair. Harriet's entanglement with Alfred, the killer, will reverberate many decades later. By 2019, Harriet's granddaughter, Libby, has made the top floor her home, but when repairs are undertaken at Calla, Libby has no idea of the danger she is in...