The phrase you used appears to be a mix of Italian and Spanish:

: While most episodes are self-contained mysteries, the relationship between Montalbano and his girlfriend Livia evolves over time. It is best to watch in order of production.

Regarding the specific mention of "del hijo" (which translates to "of the son" in English), there might be a misunderstanding or a need for clarification. The series primarily revolves around Commissioner Montalbano, and while family dynamics are part of the show, there isn't a specific series titled or focused solely on his son.

While some retailers sell box sets containing the first 26 or 34 episodes, the true "complete" collection includes every mystery from The Snack Thief to the final 2021 episode, The Catalanotti Method . Why "Del Hijo"?