(Business 2.0) – Hollywood has a formula for summer blockbusters: Spend an ungodly sum in hopes of making a whole lot more. But ROI-wise, nothing beats the low-budget sleeper that rakes in hundreds of millions. This year's surprise hit could be Rock School, a documentary about a metalhead music instructor who teaches kids how to shred Led Zeppelin tunes. The film, which opens June 3, is the first release from The Passion of the Christ distributor Newmarket Films since it was acquired in March by New Line Cinema and HBO Films (both divisions of Business 2.0 parent Time Warner). The as-yet-unnamed venture is one of several imprints vying to become "the next Miramax" after Disney's split with indie kings Bob and Harvey Weinstein.