Chakotay and Harry Kim are in an alternate future.
Fifteen years in the future, Chakotay and Harry Kim find Voyager frozen beneath the ice of a distant planet, its crew long dead. They revive the Doctor and explain that the ship crashed during an attempt to use a quantum slipstream drive to get home, a flight in which Kim's calculations led the Delta Flyer while Voyager followed. Now fugitives, they plan to send a corrected signal back in time using a stolen Borg temporal transmitter.
Pursued by the USS Challenger under Captain Geordi La Forge, they carry on, and a first attempt fails. On the second try, they send the past Seven of Nine data that makes the slipstream collapse safely, leaving Voyager unharmed in normal space and years closer to home. Janeway then has the slipstream drive dismantled. The fifth-season episode, the series' hundredth, centres on Kim's guilt, and it ends with Kim receiving a message of encouragement from his future self.