Critical by Robin Cook

Last seen in 2006's Crisis, New York City medical examiner Laurie Montgomery diligently investigates an abrupt rise in infection deaths at the start of bestseller Cook's lively new thriller. All the deaths can be traced to three Manhattan hospitals owned by Angels Healthcare. Unbeknownst to Montgomery, Angels, which specializes in high-profit surgeries of amply insured patients, is on the verge of going public and can't risk any bad publicity. She's also unaware that Angels' main financial backer is a local Mafia don, who's prepared to kill anyone standing in the way of his investment.