Not a film but a 3 series (back to back) 'The Tunnel'.
If you love a good detective type story, don't mind a bit of gore & some bad language and haven't seen it, do try it!
It starts with a maintenance worker going thru the channel tunnel and he comes across a dead body so he radios to HQ for help. They, of course, ask if it's on the French side or the English side, and he says both as the body is placed across the midway line. So both English and French cops attend.
And that's all I'm saying....
There is some French spoken in it but there are English subtitles.
Stephen Dillane & Clemence Posey (she played Fleur in Harry Potter) are the leading roles!
We're watching it on Britbox but I'm sure it's on Netflix, too.