One of the more confusing and “hard SF” episodes of Voyager that actually a) makes sense and b) kicks ass.
Using Slipstream technology, Janeway and the gang try and zip back home. Chakotay and Harry are sort of tugging them along. But Harry effs up and Voyager crash lands on an ice planet and dies. But 15 years in the future, a guilt-ridden Harry uses Borg technology to “right” the timeline.
Cool stuff and actually well told with multiple timelines (and a Geordi LaForge cameo!)