A boy called Tharen is jealous of his girlfriend Careel's admiration for He-Man, so he tricks her into thinking he is He-Man's secret identity in the hope that she'll like him better.

Meanwhile, at Eternos jail, a criminal scientist caled Galen Nycroft has managed to teleport to his cell a strange machine to increase his power. The machine transforms him into Modulok, and he escapes from jail and sets out to capture He-Man, in the hope of convincing Skeletor to recruit him. He overhears Tharen telling Careel that he is He-Man, and captures him, thinking he is He-Man's alter ego! Can the real He-Man rescue Tharen... and will his real secret identity be threatened in the process?