"Unimatrix Zero" - An enclave of Borg drones create a virtual escape, a paradise of freedom and nature, which they enter mentally through their regeneration cycles, but which vanishes from memory when they awake. Janeway recognizes this mutation as a potential crevice through which Borg resistance may be encouraged - and with Seven of Nine embarks on an undercover entry into the Borg transponder to plant a target virus.
Starring Kate Mulgrew as Captain Janeway, Robert Beltran as Chakotay, Roxann Dawson as B'Elanna Torres, Robert Duncan McNeill as Tom Paris, Ethan Phillips as Neelix, Robert Picardo as The Doctor, Tim Russ as Tuvok, Jeri Ryan as Seven of Nine, Garrett Wang as Harry Kim.
Guest Starring Mark Deakins as Axum, Jerome Butler as Korok, Joanna Heimbold as Laura, Tony Sears as Borg Drone, Ryan Sparks as Alien Child.
Special Guest Star Susanna Thompson as the Borg Queen.
This episode was directed by Allan Kroeker. The story was by Mike Sussman. The teleplay was by Brannon Braga & Joe Menosky.
TV Guide online synopsis: Seven of Nine is drawn into a dreamworld that Borg drones inhabit during their sleep cycles - a threat to the Borg Queen's control that Janeway wants to exploit.