Aliens in the Sky is the fourth novel in the Spooksville series. The summary on the back cover reads:

Vishal is awesome


After a heatwave strikes Spooksville, Adam and the gang decide to follow Sally's suggestion and head up to the reservoir to cool off. A climbing accident renders Cindy with a sprained ankle, and while she recuperates, two saucers appear overhead and proceed to land nearby. When four aliens emerge from the UFOs, Watch decides to approach them out of curiosity, and they lead him onboard. Adam and Sally attempt to convince two of them to give Watch back, but Sally upsets them and they render both of them unconscious. Cindy, watching from afar, tries to apprehend the other aliens in an attempt to create leverage, but the other two aliens are subdued by a mysterious source. Before Cindy can find out more and return to save her friends, the original two aliens abduct Adam and fly. Both ships approach a planet resembling Earth, but with dozens of space stations orbiting around it. On their respective ships, Adam and Watch hypothesize that the planet may be too polluted to support life, while Sally and Cindy are more concerned about Ekwee12's intentions and continue to ask him about his plan. Ekwee12 explains that he will use a "youth network" to relay a telepathic message that Adam and Watch are being held against their will, as this violates their world's laws. Sally implores that instead of a peaceful observation mission, Ekwee12's teachers (the aliens who initially abducted Watch and Adam) intended to kidnap aliens for the government, and that they will not allow Ekwee12 to tell the public. Ekwee12, dubbed Ek for short by Sally, hopes this is not the case, but is now suspicious of its' teachers' intentions. When Ek cannot find Adam and Watch using a computer, Sally decides to concoct a bluff by threatening the space station with the unstable and explosive fuel, Zelithium 110, used to power the ship.

Adam and Watch are detained in a cell similar to a cage in what appears to be a zoo; present are other species, including Hyeets, which implies Sally's theory is correct. However, they are quickly approached by Zheekee191, who uses telepathy to explain that he is a friend of Ekwee12's and received the message about their kidnapping. They escape from the zoo and take advantage of the aliens' general naivety to make their way to space station, where Adam makes a bluff of his own using an obtained laser gun. Meanwhile on the ship, Ekwee12 elevates the reaction of the Zelithium 110 to dangerous levels in order to force the aliens to produce Adam and Watch. When Adam and Watch appear, Sally commands Ek to stop the reaction, but it bypasses the controllable level and is set to blow up everything in a one thousand mile radius. Sally offers to help pilot the ship away from the space station to neutral space where it can explode without causing harm, but Ekwee12 programs it to do it itself. They get everyone off of the ship and watch the ship fly into the distance, no aftershock or explosion in sight.

Once on land, the gang is taken captive by the government, despite the protests of Zhekee191 and Ekwee12. When all seems lost, a large number of young aliens appear in protest and demand that the humans be freed. Because the younger population have voting rights in this society, the government is forced to comply and they let Adam, Sally, Watch, and Cindy go. Ekwee12 pilots the gang back to Earth and asks if they would like it to transport them to a specific point in time. When questioned about this capability, Ek reveals that the ship traveled through time and that the planet they saw was still Earth, but thousands of years in the future. The aliens that the gang saw were actually evolved humans, and the pollution of the planet occurred years ago, in the gang's future. Adam vows to help prevent this from happening. Ekwee12 then explains that the reason they were kidnapped was to be studied by the "aliens" in order to learn more about their past selves. It promises that the youth of future Earth will not allow any more intelligent beings to be kidnapped against their will.

They return to Spooksville slightly before the alien landing on Cindy's insistence; she uses this opportunity to stun the aliens that had been mysteriously stunned earlier. The gang then says their farewells to Ekwee12, who promises to visit again. They wanted to know if they could go with the aloen called Ekwee12, so they went with them then died kyra +neyhan.