Question: who plays sierra in the affair season 4
Answer: on as Yvonne , a publisher who , along with her husband Robert , owns the guest house in which Alison and Noah stay ( season 2 ) Peter Friedman as Robert , Yvonne 's husband ( season 2 ) Abigail Dylan Harrison as Stacey Solloway ( season 3 -- present ) Brendan Fraser as John Gunther , a prison guard ( season 3 ) Reagan and Savannah Grella as Joanie , Alison and Cole 's daughter ( season 3 -- present ) Christopher Meyer as Anton Gatewood , an intelligent student at the school where Noah teaches ( season 4 ) Emily Browning as Sierra , Helen and Vik 's neighbor ( season 4 ) Ramon Rodriguez as Ben Cruz , a Marine veteran and Alison 's love interest ( season 4 ) Zenobia Shroff as Priya Ullah , Vik 's mother ( season 4 )