Her theatre projects include Tube, Angela Carter, The Subtle Art of Boiling Lobsters, Amaretti Angels and Modern Dance for Beginners.
לתיאטרון כתבה פלפס את המחזות "Tube", "אנג'לה קרטר", "The Subtle Art of Boiling Lobsters",‏ "Amaretti Angels" ו-"Modern Dance for Beginners".