Some locations that are problems that they know about -- a central locations that is the real problem, and which they learn about --
How many of the first do they have to visit? When do they make their discoveries? Who opposes their not checking them all if they conclude they have enough information to cut to the second? Given that they have been sent by authorities -- and they have used that authorization freely -- other characters can seriously crimp their planning.
Would a high level outline help -- higher than scene by scene? I would have to continue the scene by scene to make sure there's a story, but the structure on this one may need some help. sigh