Tae-sang, left alone after his mother's extramarital affair and consequently his father's death, lived through a deprived childhood. He rose to second in command with the help of his mafia boss, but is betrayed by him out of jealousy and suffers a near-death crisis. In the end, he rises to the top after eliminating his boss and becomes a successful businessman on entering the loan industry. He plans to prepare a cultural business for the woman he loves, Mi-do. Mi-do, well-rounded and accomplished, grew up strong-minded in spite of her family's poverty. Being aware of others' snobbishness, she is full of ambition to live a lavish life others willl envy, but feels the wall between her desire to rise in status and reality. Mi-do, who had received Tae-sang's support, realizes his thougthfulness was actually love. About to consider even marriage, she develops feelings toward Jae-hee who she met while on a trip, as if he were her destiny. Jae-hee, while he has feelings for Mi-do, wishes to repay Tae-sang who helped him attend a prestigious university and become confident in his own right. 'When a Man Loves' with Han Tae-sang, the ex-gangster turned successful businessman and the woman he loves, Seo Mi-do. And the new man who sways her heart, Lee Jae-hee. A melodrama portraying a dangerous and deadly love triangle formed by the three.