British television star Billie Piper is to make her debut at the National Theatre this fall in Lucy Prebble\'s new play, \"The Effect,\" producers announced. Starring Jonjo O\'Neill, Tom Goodman-Hill and Anastasia Hille, the play by \"Enron\" scribe Prebble explores questions of sanity, neurology and the limits of medicine, the BBC said. The new show is to open at the National\'s Cottesloe location. Piper, 29, is a pop singer known for her small-screen acting roles in the drama series \"Secret Diary of a Call Girl,\" which Prebble also penned, as well as the science-fiction staple \"Doctor Who.\" Piper\'s stage credits include Christopher Hampton\'s \"Treats\" in the West End and Neil LaBute\'s \"Reasons to Be Pretty\" at the Almeida Theatre.