In the Midnight Hour. Only Murders in the Square, #1

An inquisitive bachelor. A mysterious widow. A dangerous partnership in Regency London. Idle heir to an earldom, Viscount Northwood drifts through life with little purpose-until a shocking murder shatters the calm of his quiet London square. His prime suspect? The beautiful but enigmatic widow across the way. Determined to uncover her secrets, North calls upon the investigative tricks he's learned from his Bow Street Runner twin.
Except anonymous broadsheets are circulating, exposing every lurid detail of the crime and bringing a crowd of intrusive onlookers into the square, complicating North's investigation. When he discovers the author of the scandalous publication is none other than the suspicious widow and that she is also apparently trying to solve the murder, they reluctantly join forces. Their uneasy alliance is soon tested when the killer sets his sights on them.
Can they trust each other in the face of danger, or will the murderer claim two more victims?