Ok, I'm going to explain this to you as well as correct your sentence. The sentence should be worded like this:
Mr. and Mrs. Douglas are at a travel agency getting some information about their tours.
Their in this sentence refers to Mr. and Mrs. Douglas. It's a posessive pronoun meaning that Mr. and Mrs. Douglas are the people and the tours belong to them, thus it is their tours.
Hope this helps.
Ali aka FLHomeschoolMommy