Complex sentence: A hunt is begun for Quesne, who has discovered that Joan Vance (Rosemary Lane), a nurse and Rhodes' sweetheart, is a carrier of the rare blood type, escapes with her in a taxi professing to be taking her to Rhodes.
Split into simpler sentences: A hunt is begun for Quesne, who has discovered that Joan Vance (Rosemary Lane), a nurse and Rhodes' sweetheart, is a carrier of the rare blood type. He escapes with her in a taxi, professing to be taking her to Rhodes.