www.makemkv.com

Bought on Amzn, episode .mpls files are:

Season/series 1
Disk 1
- Episode 1: 932
- Episode 2: 769
- Episode 3: 921
Disk 2
- Episode 4: 939
- Episode 5: 252
- Episode 6: 950

Season/series 2
Disk 1
- Episode 1: 383
- Episode 2: 798
- Episode 3: 964
Disk 2
- Episode 4: 946
- Episode 5: 204 ...

I had a bit of extra time this weekend, so I answered my own question. Here's the mpls list for Grantchester series 4 if anyone's interested:

Disk 1
episode 1: 266
episode 2: 802
episode 3: 777

Disk 2
episode 4: 409
episode 5: 268
episode 6: 750

Has anyone figured out the obfuscation for Grantchester series 4 yet?

Thanks!