Complex sentence: The success of the Falconer-Gantry team is mired by Lulu Baines (Shirley Jones), a former girlfriend of Elmer's who fell into disrepute and became a prostitute when her affair with Gantry ruined her standing in her minister father's eyes.
Split into simpler sentences: The success of the Falconer-Gantry team is mired by Lulu Baines (Shirley Jones), Elmer's former girlfriend. Baines fell into disrepute and became a prostitute when her affair with Gantry ruined her standing in her minister father's eyes.