Are you planning on going back to 1920's on Earth with only humans running around or can it be a totally different dimension with all kinds of aliens and for example a demolished city?  I'm just shooting ideas here! 

Whatever the setting, they must first locate the STS beacon or at least follow the signal, right? We can go from there. I'm actually hoping they find something very disturbing or creepy or perhaps get set up by their own government OEEEEH!