The Art of Death by David Fennell 

Death is an art, and he is the master . .
. Three glass cabinets appear in London’s Trafalgar Square containing a
gruesome art installation: the floating corpses of three homeless men. Shock
turns to horror when it becomes clear that the bodies are real. The cabinets
are traced to @nonymous – an underground artist shrouded in mystery who makes
a chilling promise: MORE WILL FOLLOW. Eighteen years ago, Detective Inspector
Grace Archer escaped a notorious serial killer. Now, she and her caustic DS,
Harry Quinn, must hunt down another. As more bodies appear at London
landmarks and murders are livestreamed on social media, their search for
@nonymous becomes a desperate race against time. But what Archer doesn’t know
is that the killer is watching their every move – and he has his sights
firmly set on her . . . He is creating a masterpiece. And she will be the
star of his show.