Deal killer

the long version

"Darby arrives in Manhattan for a much-anticipated visit with Miles Porter -- and to find a dream property for her client Hideki Kobayashi -- only to learn that Miles is a suspect in a murder investigation. Russian businessman Alec Rodin was stabbed to death near Miles' office after a public confrontation between the two men. It doesn't help matters that Miles and Rodin's fiancée live in the same ritzy apartment building. Darby and Miles set out to find the killer. It seems that everyone connected to Central Park Place has something to hide. There's Natalia Kazakova, the victim's not-very-distraught fiancée and her billionaire father, Mikhail, who owns the penthouse suite where she lives. Members of Russia's shadowy security force, a desperate real estate agent, the reclusive old woman in Apartment 515 -- who can be trusted?" -- from publisher's web site.