For Doctor Mather, Sky Serum day means dull parties, another lonely night, and working overtime at the hospital. For assassin Joe, he doesn't have time for silly celebrations. Neither men expect their lives to change with one blast and a snowman cookie. As the height of Sky Serum Holiday commences, Joe responds to a cave-in. The feared member of the H.S.P.C. doesn't want to be anyone special and when he saves a doctor trapped in the underground den, Joe discovers the joy of being "Jack". A no one. Just a friend. Right as Doctor Mather Stone thinks this celebration will be like all the others, a blast rocks his world. As Mather accepts his death, a stranger saves him, altering his life forever. "Jack" and Mather start off as strangers, but their time together as friends grows into more. Problem is, Joe isn't who he says he is, and Mather is suspect in the Earth Den bombing. But fate is in no hurry to change the slow and easy love building between them.