Let me start by saying it is a spy thing. Not everyone's cup of tea.
The premise is Slough House, where spies have screwed up enough to be punished but not enough to be kicked out of the service (MI5). Stars Gary Oldman as the old spy master running the house. It has a good cast beyond that, but it's probably the best-known name in the mix.
Not to give anything away, but standard Spy stuff, betrayal, death, stuff happens.

To give something to chew on, really, really good. I thought I would give it a try. The first episode was pretty good. Binge watched the entire first season in one night.
The second night, the second season, and last night, the third. Wouldn't let myself go to sleep even though it was after midnight and I have to be up at 7, because I wanted to finish the season because it is an on the edge of the seat set.
It has been greenlighted for a 4th season.
If modern spies is your interest, give it a look. These are not the best people, let us just say that.