Shetland: Series 4

Season overview

Role: Meticulous television and film archivist.
Task: Produce a JSON object for "Shetland" Season 4.
Constraints:
Use ONLY provided SYNOPSIS and SOURCES.
No invented facts (titles, names, dates, etc.).
If not in material, omit.
Style: Original, neutral, encyclopedic prose, plain text.
Format: Valid JSON only, no markdown, no asterisks, no headings, no bullet points.
JSON Keys:
overview: 160-220 word summary of the season's narrative arc.
primer: Array of exactly 4 concise bullet points (essential previous lore/characters/stakes).
TMDB Synopsis: "A convicted killer's return to Shetland after 23 years in jail coincides with the murder of a local journalist and Perez and his team must investigate both cases."
Source [1]: Created from novels by Ann Cleeves.
Source [2]: Created from novels by Ann Cleeves. Follows DI Jimmy Perez and his team investigating crime in a close-knit island community. Isolated and inhospitable environment. Resourceful style of policing.
Source [3]: Mentions fictional detectives Jimmy Perez, 'Tosh' McIntosh, and Ruth Calder.
Source [4]: Cast includes Ashley Jensen, Douglas Henshall, Alison O'Donnell, Steven Robertson.
Source [5]: Mentions it is a BBC show.
Overview (Target 160-220 words):
The narrative of Shetland season 4 centers on two simultaneous investigations managed by DI Jimmy Perez and his team. The season begins with the return of a convicted killer to the Shetland islands following a twenty-three year period of incarceration. This individual's homecoming occurs at the same time as the murder of a local journalist. Perez and his team are tasked with investigating both the circumstances surrounding the journalist's death and the implications of the returning convict. Set within an isolated and sometimes inhospitable island community, the series continues to explore crime through a uniquely resourceful style of policing. The investigations take place within a close-knit environment where the team must navigate the complexities of the local population. As the team works to solve these cases, they must deal with the tensions inherent in a community where murder is only a ferry ride away. The series is based on the crime novels written by Ann Cleeves and follows the professional lives of the detectives as they handle these overlapping criminal matters in the Shetland landscape.

Word count check:
1. The (1)
2. narrative (2)
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