This is both parts of a two part Masterpiece mystery. For PBS/BBC fans of the program, this is top notch as you might expect. For non fans, better to choose something else. A bit grainy as it was transcribed from the British scan rate standard to the much lower US standard. Almost too many sub plots for me, but they were finally, perhaps painfully, resolved. Bonus for Helen Mirren fans: we get a quick shot in the obligatory gratuitous sex scene. I could do without the S&M scene although the issue is essential to tie the threads.
This two part series gives Helen Mirren the opportunity to show her many talents and personalities. You must sit and pay attention or you will miss something and have to "go back again" A must for your Helen Mirren collection.