This is what I picked up from the first preview alone (not the second one, any of the clips, or any synopsis online).
A Knight (Cage) is given a task to take an evil witch who can see people's worst fears and do all kinds of crazy witchcraft to a temple where they can heal her. He is given this task because he was so freakin' awesome against some Turks during the Crusades. An elite band of knights is assigned to help him out (I'm guessing one will be really green and be given a hard time by the others but that is only a guess). Along the way she does a bunch of witchy crap that kills off a lot of the group (apparently summoning wolves at one point) but good ol' Nicholas won't let that stop him (also being immune to the witch's powers by the grace of god). They finally reach the abbey and walk inside only to find all the monks are killed/enslaved to the witch's power (couldn't really tell but does it really matter?) and she melts the bars of her cage to escape. She then attacks the party probably (more guessing) leaving Cage and another guy (maybe the green kid) alive for the final showdown before Cage finally is able to bring it all to a glorious and heroic finale.
Now whoever wants to go pay $10 to see this movie can let me know how I did because except for the parts where I admitted I was guessing this was ALL FROM THE FIRST PREVIEW. C'mon people, I'm so sick of previews being a summary of the entire movie and not leaving anything secret.