Kes finds herself in Sickbay, on the verge of death. The Doctor activates something he calls a bio-temporal chamber and Kes experiences a shift in perception. She finds herself with a boy — apparently her grandson Andrew — who gives her a belated birthday gift. The Doctor tells her he's going to put her into the bio-temporal chamber to prolong her life. She's in the Morilogium, the final phase of the Ocampan lifespan. Suddenly Kes . . .
. . . awakens in her quarters, where Andrew is still working on the present that he already gave her. Kes meets Linnis, her daughter, who is married to Harry Kim. Linnis' father is Tom Paris, who is also Kes' husband. As Kes tries to take all this in . . .
. . . she finds herself celebrating her ninth birthday with her family and friends. Andrew tells her he hasn't had a chance to begin working on her present. Bewildered, Kes tells the Doctor that she seems to be experiencing life in reverse. Consulting her medical records, Kes learns she suffered from chronoton radiation poisoning when Voyager was under attack by the Krenim. As Kes reasons that the radiation exposure may explain her condition . . .
. . . she experiences another jump. This time she goes immediately to the Doctor, who confirms that the chronoton particles, reactivated in the future by the bio-temporal chamber, are moving her backwards in time. To stop the jumps, they must purge her of the radiation — and the only way to do that is to find out the temporal variance of the Krenim torpedo that contaminated her.
Kes continues jumping back in time . . . to the birth of Linnis . . . and to the Krenim attack, when she was exposed to the radiation. Finding the torpedo, she notes the temporal variance, then jumps again . . . to a year earlier, where she warns Janeway to avoid Krenim space and gives the Doctor the information to program a bio-temporal chamber that will purge her system. As the chronoton count begins to drop, Kes experiences several more jumps . . . eventually arriving at her moment of conception. Just as she ceases to exist, her body is purged and she awakens back in the period in which they were using the chamber to eliminate the chronoton particles, where she happily notes there's no time like the present.