Margot Arnold is the pseudonym of Petronelle Marguerite Mary Cook. She was born in Plymouth, Devon, England. She received a B.A. with a Diploma in Prehistoric Archaeology and Anthropology in 1947, and an M.A. in 1950 from Oxford University. She is a long-time resident of Hyannis, Massachusetts. She is a mystery fiction writer, creator of the Dr. Penny Spring and Sir Toby Glendower series, about an anthropologist and an archeologist based at Oxford University, England.A former longtime resident of Cape Cod, she now lives in Bethlehem, Pennsylvania.