NEW YORK - Linda Stein beat cancer, survived the Bowery's seedy punk-rock scene and thrived amid the high-stakes world of Manhattan real estate. Her sudden death Tuesday came in an unexpected way and place: violently, inside her $3 million Fifth Avenue apartment.

The brutal bludgeoning of the Stein, 62, dubbed the "Realtor to the Stars" in the years after she quit rock 'n' roll for real estate, left behind shaken friends and family as police searched yesterday for her killer.

A team of detectives was interviewing employees at her posh doorman building, and reviewing security videotape.

Friends like Madonna and Elton John recalled Stein's indomitable personality, and her triumph against breast cancer. Other celebrity friends and clients included Sting, Billy Joel, Steven Spielberg and Angelina Jolie. Stein was at the epicenter of punk rock, co-managing the Ramones. *