Fans of "The X-Files" will have to wait an undetermined amount of time before the show returns to television, if it does at all, to learn the fate of Agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson), which were so cruelly left up in the air when the series' revival season concluded earlier this year.

But the situation isn't all grim. Come Jan. 3, X-Philes will get a chance to dig into the pasts of their favorite paranormal investigators with two young-adult novels, both set in 1979, which will...