I can tell the difference between who I am and a side effect. The Effect is a clinical romance. Two young volunteers, Tristan and Connie, agree to take part in a clinical drug trial. Succumbing to the gravitational pull of attraction and love, however, Tristan and Connie manage to throw the trial off-course, much to the frustration of the clinicians involved. This funny, moving and perhaps surprisingly human play explores questions of sanity, neurology and the limits of medicine, alongside ideas of fate, loyalty and the inevitability of physical attraction. Following on from the critical and commercial success of Enron, The Effect is the latest play from Lucy Prebble, and reunites Enron's writer and director once more delivering a vibrant theatrical exploration into the human brain via the heart. This world premiere is co-produced by Headlong and will be performed at the National Theatre's Cottesloe Theatre from November 2012-23 February 2013, starring Billie Piper and Jonjo O'Neill. The Guardian has selected The Effect as one of the highlights of 'the best theatre for autumn 2012' (2/9/12).