Only when they move into their bargain new house do the Lawfords (Dad, mom, Josh, 11, and Annie, 9) learn that because of a bureaucratic snafu they were thought to have agreed in advance to operate this location as an arrival and departure depot for tourists of many species from around the universe who will "beam" in and out via an object in the ground out back, not in spaceships. As depot hosts they must help the visitors with disguises, caution them about absolute no-nos, and keep all other uhmans safe from them and them safe from the humans who won't know there are alien creatures vacationing among them. The family must decide whether to agree to do that or to have their memories wiped and lose the house. They opt to try it. Their first guests, creatures called Trubs, are uncooperative to the point of putting their own lives and the intergalactic travel program in danger but they also have needs and quirks that the Lawfords use to limit and control them to some extent. The main hassle is that the Trubs refuse to leave at the scheduled time and intend to wander more and farther on their own. A kind of situation experienced tour guides must deal with now and then even if their guests don't drink kerosene.