This paper presents a worldsheet theory describing holomorphic maps to twistor space with  fermionic directions. The theory is anomaly free when  = 8. Via the Penrose transform, the vertex operators correspond to an  = 8 Einstein supergravity multiplet. In the first instance, the theory describes gauged supergravity in AdS4. Upon taking the flat space, ungauged limit, the complete classical S-matrix is recovered from worldsheet correlation functions.