If that alien spoiler has any truth to it, here's how I predict the movie will go down...
Indy is now the dean of Barnett College. He returns home to find his son watching the TV, featuring a program about the Roswell crash. Indy, who is disturbed that his son is more interested by things like TV and science fiction than learning history, says "You don't believe that nonsense, do you?" Indy Jr., who is relatively in the dark about his dad's adventurous past, says "Dad, this is way more interesting than teaching at some stuffy college!" Brief father/son banter ensues.
The next day at the college, a package arrives from South America. Enclosed is a bizarre skull with a note that claims a discovery has been made at some temple. Indy considers himself too old to be running around the globe, but sees that the note is from Marion Ravenwood, so he figures he might pay her a visit.
Indy Jr. hears about the trip, and insists on going. Indy protests, claiming that it's college business and that he needs to stay home and study. But, after Indy Jr. says that they never get to do anything together, Indy thinks back to his own childhood when his father often ignored him in favor of work-related pursuits. So, Indy agrees to let his son tag along.
Along the way, Indy Jr. will see the skull, and mention that it bears some similarity to some alien related sci-fi stories he's heard, and Indy will just brush it off and tell him to not get too absorbed in such fantasy.
At the dig site, Marion will appear and briefly reminisce with Indy, and then mention that they've found some strange carvings in a newly excavated room. Indy Jr. will get bored and walk around the dig site. Indy says "Just don't touch anything!", to which Indy Jr. gives a sarcastic "Yeah, yeah". After awhile, Indy Jr. comes running back and yells "Dad, come look at this!" and brings him to one of the excavation rooms. There are some engravings that Indy Jr. recognizes from some book he's read, and as he leans in closer to examine them, he accidentally knocks something over that slams into wall, collapsing it. As the dust settles, a hidden door is revealed that leads to a few new chambers.
Somehow, as they search deeper into the site, Indy becomes impressed that his son is actually a lot more knowledgeable than he thought. As the plot advances and various dangers pop up, Indy Jr. is impressed that his dad is a lot more resourceful and strong than he imagined.
At the end, Indy Jr. will give his dad an awkward glance as he kisses Marion, and shortly afterward some younger girl will kiss Indy Jr., evoking the same response from Indy.
