^^^which particular storyline? with the inhumans? or with the mutants? or with marvel in general, avengers characters, etc?
for the inhumans---you would read secret invasion: inhumans, and war of kings...both of are which are not really worth buying imo
for mutants: you should get messiah complex next
marvel in general-civil war
i would say to just read whedon and cassady's astonishing x-men...because you're about to get into super-mega-event-crossover territory with civil war, world war hulk, secret invasion, seige...it gets pretty convoluted imo
which characters or writers or artists are you interested in specifically?