Seven of Nine is separated from the Collective.
The Borg accept Janeway's offer of a nanoprobe-based weapon against Species 8472 in return for safe passage, and they assign a spokesperson drone, Seven of Nine, to deal with the crew. When a bioship attacks, the Borg cube rams it and is lost, leaving Seven and a group of drones aboard Voyager while a gravely injured Janeway undergoes surgery. Chakotay, left in command, plans to put the drones off on a planet, but Seven opens a rift that drags the ship into fluidic space, the realm of Species 8472.
Janeway recovers, takes back command and puts Chakotay in the brig to placate the Borg. The finished weapon drives off the bioship fleet and forces Species 8472 to withdraw. When Seven then tries to assimilate the ship, a prepared trap severs her from the Collective. The episode opens the fourth season and brings Seven of Nine aboard as a lasting member of the crew, changing the series for its remaining years.