The WB Network, home to such clean-cut fare as “Everwood” and “Smallville,” is developing an original movie about late rock icon Kurt Cobain, the troubled frontman for “grunge” band Nirvana. The network has obtained the rights to Charles Cross’ 2001 book “Heavier Than Heaven: A Biography of Kurt Cobain.” Robert Munic (“They Call Me Sir”) has been commissioned to write the script for the untitled film, which could get a primetime berth as early as next season. Cobain killed himself 10 years ago. “The day Kurt Cobain died was the day the music died for a generation,” said Tana Nugent Jamieson, senior VP of the WB’s new longform original programing unit. “His story is perfect for our audience.” No casting or director is attached. The film will trace Cobain’s life from his troubled youth near Seattle to his pioneering role in the emergence of the grunge music genre as the lead singer and guitarist of Nirvana. Taking its cue from Cross’ unauthorized bio, the film will detail Cobain’s bouts with depression and drug abuse as well as his turbulent relationship with rocker wife Courtney Love. Jamieson hopes to give the film a cautionary tone, with a public-service announcement on the dangers of depression possibly following the film. “We can do this right without seeming preachy,” she said. Munic said the film was “not your traditional biopic,” noting that “the storytelling will have a nonlinear style, flashing to different parts of his life out of chronological order.”