Rapture and Pro Muscle are both scientists at a laboratory. They’ve been working on a growth serum that abruptly had funding cut off. Angry, Pro Muscles defiantly drinks down a dose of the serum while her co-workers watch. It only takes seconds for it to kick in, and as it does, she begins to grow bigger. Her muscles get bigger by the second, and her co-workers begin to get scared when her muscles start to rip through her clothes. By the time she is done growing, her clothes are in tatters.