Best Selling Secrets (Traditional Chinese: 同事三分親) is a TVB modern sitcom series broadcast from March 2007 to August 2008.

Wong Ka-Nam (Esther Kwan) disappeared to the United States, leaving behind her son and husband in Hong Kong.

When her husband dies in an airplane accident looking for her, Wong Ka-Nam's son, Luk Chit (Vin Choi) is taken into the custody of her mother-in-law, Ng Hang (Elaine Jin).

Highly protective of her grandson and fearing that Wong Ka-Nam will attempt to take him away, Ka Nam's mother-in-law does everything in her power to keep mother and son apart.

However Wong Ka-Nam is ironically assisted by her own son, who befriends her and secures her office job in his advertising agency.