The Doctor transmits his program to Jupiter Station to treat his ailing creator, Lewis Zimmerman.
Through the Pathfinder link, Voyager learns that Dr. Lewis Zimmerman, the creator of the Doctor's program, is dying of an illness Starfleet doctors cannot cure. Believing his years in the Delta Quadrant give him a fresh view, the Doctor has his program sent to Earth over the link and arrives at Zimmerman's research station near Jupiter, where Reginald Barclay is caring for the scientist.
Zimmerman is bitter, sees the Doctor as an outdated Mark I and refuses to be examined. The two clash repeatedly, until the Doctor's program begins to fail and Zimmerman has to repair it. As they argue, Zimmerman reveals how wounded he was when his Mark I holograms were judged failures and sent to do menial work. Finally he lets the Doctor treat him with a therapy developed on Voyager, and he recovers. The sixth-season episode casts Robert Picardo as both the Doctor and his creator and is a story about a father and son reconciling.