This season saw the show embracing the notion of serialized storylines. A recurring theme throughout the season is the notion of a brewing Duras-Romulan plot against the Federation, coupled with Worf's effort to reclaim his family honor. Both storylines were introduced in Season 3's "Sins of the Father". Worf's discommendation is a major theme in "Family" and "The Drumhead", while his dishonor and the Duras-Romulan plot take center stage in the episodes "Reunion", "The Mind's Eye", and "Redemption".
A second recurring storyline in the season is the growth of Miles O'Brien as a character. His first and middle name are revealed in "Family", he marries in "Data's Day", his past is revealed in "The Wounded", and his marriage is explored in "In Theory".
Season 4 featured many family-themed episodes. The first episode following "The Best of Both Worlds" deals with Picard and Worf's family, and the second with Data's. Worf's son Alexander appears later in the season, as does Tasha Yar's sister, and the Enterprise encounters an infant alien space entity.
Picard is rescued from the Borg as the Enterprise races to save Earth. Data interfaces with the half-Borg Picard and finds a way to shut down the Borg ship. Guest star Elizabeth Dennehy as Starfleet Commander Shelby.
While the Enterprise is undergoing repairs at Earth, Captain Picard visits his brother's family in France, Lt. Worf's adoptive human parents come to see him aboard the ship, and Dr. Crusher gives her son Wesley a personal holo-recording left by his late father shortly after his birth.
After an apparent failure of a warp-field experiment, people begin to disappear from the Enterprise with only Dr. Crusher remembering that they ever existed.
Data gets dancing lessons from Dr. Crusher in preparation of Chief O'Brien's wedding as the Enterprise brings Ambassador T'Pel to the Romulans for negotiations.
A powerful mythic figure from a millennium ago returns to enslave a planet in accordance with a contract. However, Picard is convinced she is an opportunistic charlatan. Guest star Marta DuBois as Ardra.
The crew, with the exception of Data, is rendered unconscious for 30 seconds after going through a localized wormhole. However, various clues suggest they were unconscious for an entire day.
The Enterprise accidentally kills a space creature, and the crew rush to save its unborn offspring. Meanwhile, Geordi meets the engineer he fell in love with and finds to his shock that she is nothing like the woman he encountered on the holodeck.
Dr. Crusher falls in love with Odan, a peace negotiator, only to discover that he is a symbiont. When his original host dies, he is implanted into Riker temporarily to finish his negotiations.