Paul Sparks as John "Ace" Merrill in "Castle Rock" Season 2. Hulu/Dana Starbard. Paul Sparks - John "Ace" Merrill. Boardwalk Empire and House of Cards star Paul Sparks appears in the cast as Ace Castle Rock ended its mostly very good first season with an unforced error of a finale that aimed for ambiguous but landed at anticlimactic. The final showdown between the two Henry Deavers got .

castle rock season 1 summary