As happens with any series that's been on as long as TNG, they start having sequel episodes and this episode is no exception. DaiMon Bok (from the 1st season episode "The Battle", this time played by Lee Arenberg instead of Frank Corsentino), seeks to avenge his son because he thinks Picard killed him while he was captain of the Stargazer. In "The Battle", he gave Picard the Stargazer back as a "gift" but at the same time used a mind probe to make him relive the incident and ruin his life. With that plan averted, DaiMon Bok lost his rank.
Now, he's back and a DaiMon again - to avenge his son, he will now kill Picard's son (which comes as a surprise to Picard since he never knew he had a son!) - his name is Jason Vigo. Picard feels he has a responsibility to protect him against Bok and goes to his rescue on Camor IV before it's too late.
But, is Jason really Picard's son?