Trying to help my grandparents find a new detective show to watch. For reference, here's what they've already watched:
Bosch
Bosch: Legacy
Beyond Paradise
Death in Paradise
Elementary
Endeavour
Father Brown
Lewis
Lie to Me
Longmire
Marple
Midsomer Murders
Murdoch Mysteries
NCIS
Poirot
Shetland
The Brokenwood Mysteries
The Mentalist
While they generally seem to prefer British detective shows, I'm not sure which ones are left to recommend to them.
Seconding Broadchurch, it’s incredible. Big Little Lies too. Poker Face arguably counts, with its Columbo-esque “just one more thing” motif. And The Flight Attendant gave me a lot more respect for Kaley Cuoco (of Big Bang Theory fame), though it’s also got some (darkly) comedic elements. Naturally, do a cursory search for all of these before passing them along: I enjoyed them, but idk what your grandparents are like…
Vera is my absolute favorite British detective show! Also really enjoyed Grandchester, especially if they liked father Brown. Line of duty is pretty good too. Unforgotten is really good as well.