building up to the climactic burst of violence 
(ROOT (S (VP (VBG building) (PRT (RP up)) (PP (IN to) (NP (NP (DT the) (JJ climactic) (NN burst)) (PP (IN of) (NP (NN violence))))))))
(ROOT (S (VP (VBG ) (PRT (RP )) (PP (IN ) (NP (NP (DT ) (JJ ) (NN )) (PP (IN ) (NP (NN ))))))))