Kes finds herself jumping backward in time several times. To stop the jumps, the Voyager crew must purge her of the chroniton radiation, and to achieve that she must find out the temporal variance of the Krenim torpedo that contaminated her. Kes continues jumping back in time to, among other events, the Krenim attack when she was exposed to the radiation. Finding the torpedo, she notes the temporal variance, then when she jumps again to a year earlier she warns Janeway to avoid Krenim space and gives the Doctor the information so that he can program a bio-temporal chamber which will purge her system.

the chroniton torpedo, stuck in Voyager's hull in as far as a Jefferies tube

In one of the eventually unrealised timelines, that known as the Year of Hell, Voyager is at maximum alert due to constant attacks by the Krenim. See DAMAGE REPORT below.

The Doctor invents the bio-temporal chamber for Kes.

bio-temporal chamber

The Doctor has an optronic error in his program and the problem takes him offline for several months in the Year of Hell timeline. In [#76 and #77 Year Of Hell], in an alternative Year of Hell, the Doctor repairs the fault.

Kes starts to give birth on a Type-9 shuttle in the alternate future known as the Year of Hell. It manages to return safely to Voyager while Voyager is under attack by the Krenim.

During the Year of Hell one of the Krenim's chroniton torpedo fragments leaks radiation into Voyager. Their torpedoes are able to penetrate Voyager's shields because they are in a constant state of temporal flux. Voyager is finally able to defend against the Krenim by remodulating the scanners through a parametric frequency to destroy the torpedo launchers before they fire. However, events in the Year of Hell as seen in this episode (and indeed most of those seen in [#76 and #77 Year Of Hell]) do not eventually occur.