unfolds with all the mounting tension of an expert thriller , until the tragedy beneath it all gradually reveals itself . 
(ROOT (S (VP (VBZ unfolds) (PP (IN with) (NP (NP (PDT all) (DT the) (VBG mounting) (NN tension)) (PP (IN of) (NP (DT an) (NN expert) (NN thriller))))) (, ,) (SBAR (IN until) (S (NP (NP (DT the) (NN tragedy)) (PP (IN beneath) (NP (NP (PRP it)) (NP (DT all))))) (ADVP (RB gradually)) (VP (VBZ reveals) (NP (PRP itself)))))) (. .)))
(ROOT (S (VP (VBZ ) (PP (IN ) (NP (NP (PDT ) (DT ) (VBG ) (NN )) (PP (IN ) (NP (DT ) (NN ) (NN ))))) (, ) (SBAR (IN ) (S (NP (NP (DT ) (NN )) (PP (IN ) (NP (NP (PRP )) (NP (DT ))))) (ADVP (RB )) (VP (VBZ ) (NP (PRP )))))) (. )))