It's a simple story, 2 or 3 immigrant brothers with a heavy accent try to kidnap Rupert Murdoch's wife. But as he is away he loans his car to a man running the papers/paper for him. The kidnappers instead go into this wrong house and kidnap a the wrong White woman.
Kidnapping is not regular at that time so the police has to make up a plan as they go along. They put money in suitcases where the kidnappers want it and then track them. They know the woman is dead, that much becomes clear very fast, but they still play along to catch the kidnappers. The kidnappers drive around the suitcase and reveal their number plate. The police track down a farm where they live. Hundreds of officers search the farm, but no trace of her is found. The older brother left fingerprints in the house where they kidnapped her from so it's quite simple to convict them even though they claim they are innocent. The 3rd brother has an alibi and is not charged.
So it's a simple story. The documentary tries to make it "deeper" by creating a culture war story. Even before revealing anything about the case the doc builds a story about a super racist UK where the cops, media, and public are eager to hunt down foreigners no matter if they are innocent or not. They interview a lot of people who attack the cops and media for being racist. Later they reinvestigate the case to show how these poor immigrants were actually, maybe, innocent and that the racist system was unfair. The older brother, Arthur, is seen as kinda guilty as his fingerprints were at the crime scene and he was a mean character. So I'm not sure what they point is exactly? UK is racist so we don't know who did it, but Arthur still likely did it? They for example reinvestigate the fingerprints, but don't talk about it. They claim the voice of the kidnapper may be from another person, and not the younger brother, because they reinterview the 1969 kidnapper in 2021 and he sounds different. Well, they don't really tell us why they think he sounds different. The accent is very unique and it's quite clear it's the same exact accent. It may have been his brother's voice instead? At any rate I don't understand what they are even reinvestigating here. They are looking at the handwriting on a document a brother filled out, but then don't clearly explain what the document even is. Anyhow, the younger brother admitted to the death in 2021. The guy who they make out to be innocent here now admits to the kidnapping. Did the confession happen right after this 2021 doc was made? It's just stupid all around. The doc is a bunch of confusing culture war stories while you barely understand the actual evidence.
The doc just jumps from point to point in a hectic matter without really giving us all evidence. And it's very hard to track the story because they don't care about it. They have an agenda and focus on it from the get go trying to muddy the case. It would be fine if they presented all the evidence first and THEN tried to build an alternative theory. But that's not their goal.