Soso was the twin sister of Burpie Upp. They resembled each other very closely, both having light hair and a lined face. After her sister's death, Soso arrived in Dick Tracy's city to seek revenge on Fresh Upp Plenty and (by extension) Little Boy Beard. Unbeknownst to Soso, the dosed coffee killed the maid and the body was soon discovered. Soso announced herself to Fresh, claiming to have only just arrived from Europe. She invited Fresh and Little Boy Beard to stay at her palatial estate and Fresh reluctantly agreed.