The reclusive world's number-one assassin Leo suddenly receives an S-rank dark-web mission — and the client turns out to be Mia, a five-year-old genius hacker girl, offering her entire allowance as payment. Mia wants Leo to protect her single mom Chloe, who is trapped in a family conspiracy. Leo means to refuse, but the moment he sees Chloe's photo, he is struck as if by lightning: she is the great love of his life, who supposedly "died in an accident" five years ago! To uncover the truth, Leo transforms into a full-time bodyguard and nanny. Father and daughter join forces — Mia controls the whole game on the dark web, while Leo crushes everything in reality with brute force. The two play pig to eat the tiger all the way, savagely abusing the arrogant chaebol family, finally awakening Chloe's memories, and the family of three mends their broken mirror.
