With the conclusion of the Challengers of the Unknown story in Adventure 497 (March 1983), the book becomes entirely reprints. This made for a very disappointing 500th issue later in the year. Such a missed opportunity.
Nor is this final chapter of the Challengers origin anything particularly special. Bob Rozakis and Alex Toth wind things up adequately, but there is nothing in the five-part tale that makes one glad it was printed.
They figure out that none of them was the intended victim, that is was a man named Johnny Green, a friend of Red Ryan, who was also supposed to be on the flight. Johnny was owed money by the casino owner Red was in debt to, and the bomb was planted so he could avoid paying off the man.
The fight in the casino is the best scene, but even still, the solution is wholly unsatisfying, with none of the team being the inadvertent cause of the crash.
The Challengers of the Unknown next appear three years down the road in an issue of DC Comics Presents. A couple of year after that they get a decent mini-series of their ownn.