In the hustle and bustle of the city's grand arcade, Elena Frei - a 27-year-old woman with a calm face but a serious look - appears to be an ordinary shopper. But behind her calm steps, a heavy secret is hidden. Elena is a member of a secret investigation team whose mission is to track down the missing jewels of a historical exhibition. In her bright yellow blouse and pink bag, she deliberately looks like an ordinary shopper, but in her mind she meticulously registers every passerby, every reflection in the shop windows, and every suspicious movement. The golden bangle on her hand is not just an ornament, but a secret communication tool with her colleagues. The story begins when Elena sees an image in one of the shop windows that should not exist - a familiar face from a past she thought she had forgotten.