a credible account of a puzzling real-life happening 
(ROOT (NP (NP (DT a) (JJ credible) (NN account)) (PP (IN of) (NP (DT a) (JJ puzzling) (NML (JJ real) (HYPH -) (NN life)) (NN happening)))))
(ROOT (NP (NP (DT ) (JJ ) (NN )) (PP (IN ) (NP (DT ) (JJ ) (NML (JJ ) (HYPH ) (NN )) (NN )))))