A Good film but disappointing for a murder mystery

Rating: 7/10 (1 December 2019)

First of all, I enjoyed the film. Loved the music and the shots. The beginning part was great, with all the shots of the house (love the house) and slowly moving up to the important scene. If you are looking for a light, entertaining film, this is a good choice. Just don't take it as a sophisticated mystery that requires your logical reasoning.
So the three stars off is because I'm a big fan of Agatha Christine, and this story is not strong enough to be called a murder mystery for me. When I see the beginning: murder inside a house with fixed suspects, questioning with each person and finding holes in their words, they just shouts Agatha to me. But then what? All threads lead to our main character Marta. Other characters seems to just stand there, fighting each other, fighting against the will. What's their role in this murder mystery? Their verdicts, or just overall story, contributed almost nothing to the mystery, except for family drama. The whole movie just feels like Marta, Ransom, and other family members, what's the fun in guessing the murderer then?
Then there's our victim. I have no idea why someone would want to leave his fortune to his nurse, or slice his own throat for her. I mean yes, they have good relationships, and he wanted his family to do their own things instead of relying on his fortune. But he can always donate, right? How close he has to feel towards Marta to leave all his fortune to her and believe she could do the right thing? Furthermore, how close their relationship has to be to let him decide to slice his throat just to cover up for his nurse? I mean that's some painful way of death. And do people commit suicide by slicing their throat? If Harlan wants to cover for Marta, surly he would choose a method looking more like a suicide, like cutting the wrist? stab into his chest? I don't know. Anyway Harlan is waaay too good to Marta, in a way beyond my normal senses.
Lastly, the twist in the end was good, but... the whole story could have ended if they saw the surveillance camera or footprints on the muddy path. I mean Ransom didn't even try to cover it up. It's just coincidence both of them went through the same path. There are way too many coincidences in this story, including this, and the double mixing up bottles, the old lady who just happened to sit by the window that faces the secret path. If Marta chose a different way of creating alibi, Ransom would have been spotted the first day of our detective's investigation. So in short, a mystery that could have been solved early on if not for an coincidence.
This film could have been my favorite of the year. I mean the genre, the beautiful house, my favorite detective style, and all the good actors, but in the end I went out of the theater feeling mixed. I guess great anticipation usually comes with great disappointment...