starts off as a potentially incredibly twisting mystery 
(ROOT (VP (VBZ starts) (PRT (RP off)) (PP (IN as) (NP (DT a) (ADJP (RB potentially) (RB incredibly) (VBG twisting)) (NN mystery)))))
(ROOT (VP (VBZ ) (PRT (RP )) (PP (IN ) (NP (DT ) (ADJP (RB ) (RB ) (VBG )) (NN )))))