offers an intriguing what-if premise . 
(ROOT (S (VP (VBZ offers) (NP (DT an) (JJ intriguing) (WHADJP (WP what) (, -) (IN if)) (NN premise))) (. .)))
(ROOT (S (VP (VBZ ) (NP (DT ) (JJ ) (WHADJP (WP ) (, ) (IN )) (NN ))) (. )))