After years abroad, the entrepreneur's daughter Isabella Meinhardt returns to Germany at the request of her widowed father Friedrich. But instead of accepting her onto the board of his automobile factory as expected, Friedrich presents his stunned daughter with his new fiancée, the public prosecutor Viola. Isabella does get a chance at the company, but not on the executive floor: she is initially expected to earn her spurs on the assembly line. Incognito, of course. She falls in love with the smart engineer Sebastian, who has no idea of her true identity.