I loved this movie. It is based on the original 1924 Agatha Christie short story. The original movie from 1958 is based on the play Christie wrote in the late 50s with Charles Laughton, Tyrone Power and Marlene D. The first Witness movie took place almost entirely in the courtroom and the barrister's office. It has some very funny bits. This version, the remake, has no funny bits.
I usually don't like remakes but I was eager to see this one because of Toby Jones and Andrea Riseborough (see Shadow Dancer for Riseborough).
This later version holds true to the original story and takes place in the 1920s, just a few years after WW1. It is a murder mystery but has twists and turns. The period setting is important--millions of men died on the front, and some million more came home to England and there were no jobs, no opportunities and great bitterness. On the other hand, the affluent were living the life of Gatsby.
Here is what I loved: the acting, the set design and lighting, London not glittering and shimmering but dark, dirty and grim cast in a dingy yellow light. I was pulled into a wounded world and I couldn't take my eyes away. I know I will see this movie again.
P.S. See Agatha with Vanessa Redgrave and Dustin Hoffman - same period, also a mystery and Redgrave plays Christie who has disappeared.