SEASON PREMIERE RESUMES AS COPS FIGHT FOR LIVES AGAINST RAGING MOBSTER; GENE SIMMONS ('KISS') RETURNS TO GUEST-STAR -- In the season premiere, the action resumes from last year's finale as an obsessed mob leader (guest star Gene Simmons from "KISS") continues to unleash his fury over his son's death by trying to kill scores of cops -- especially Detective Cruz (Tia Texada). As the NYPD reels from his attacks, four masked gunmen scythe through the hospital jammed with the wounded. The gun battle rages over multiple floors and Bosco (Jason Wiles) is critically wounded -- causing Cruz to wonder if a fellow cop is in league with the mobsters. Meanwhile, Kim (Kim Raver) is repulsed by the carnage despite some exciting news. Cruz and a large contingent of police officers are at the hospital dealing with a witness, their own injuries and other victims from two separate bombings. Suddenly, four men with bulletproof vests and submachine guns arrive and cause carnage as they try to obliterate the cops and kill the man who can implicate the killing spree's mastermind, vengeful father Donald Mann (recurring guest star GENE SIMMONS of the rock group KISS). Davis endures a mighty hand-to-hand struggle with one of the assassins. Kim saves two innocent bystanders. Sullivan, Monroe and Carlos battle to penetrate the shooters' defenses. Grace tries to protect doctors, nurses and patients in an operating room. And Bosco is gravely injured shielding Yokas. But Cruz manages to capture one gunman and forces him to reveal a crucial clue to Mann's whereabouts. Followed by the distraught Yokas, Cruz sets out to find a traitor within the ranks--and somehow stop Mann before he flees the country. Meanwhile, in the midst of her ordeal at the hospital, Kim copes with the news that she is pregnant. She tries desperately to contact her boyfriend, firefighter Jimmy Doherty (former series star EDDIE CIBRIAN), and finally reunites with him at the station house. He emotionally proposes marriage to her--again--and, this time, she accepts Coby Bell, Eddie Cibrian, Nia Long, Molly Price, Anthony Ruivivar and Skipp Sudduth also star. TV-14.