Edmond O'Brien did not receive an Oscar nomination for portraying Frank Bigelow in D.O.A.
O'Brien the king of thankless roles really gets another here even though he is the one and only lead this time. O'Brien though does still have a thankless role as Frank Bigelow who is the man trying to find out who poisoned him and for what reason. Before he is poisoned he is just a very average man and notary. O'Brien is just fine at being normal guy being normal. He is likable enough even though he is hampered a bit by his love interest who stands as a sore spot throughout the film as she just is not an interesting character, and she is rather poorly played by Pamela Britton. The normal man though is quickly thrown into a film noir plot by finding out he only has a few days to live.
The soon to die aspect again is rather thankless as it is not something that he gets to dwell on for long he has to go head first into the investigation while feeling to anguish of the fact that he is going to die very soon. O'Brien though is very good in what he is able to get out the role despite the rather extreme limitations of the set up. O'Brien is quite intense as he portrays Bigelow basically freak out as he tries to figure out how he so suddenly has gotten himself in a situation. The intensity is absolutely earned considering the situation and it really would have been very wrong for an average guy like O'Brien to treat this development in a quiet or even moderate fashion, the extreme method O'Brien takes fits the extreme situation his character is in.
O'Brien is effective as after the initial anger and confusion he expresses he shifts to a man who always has a directive within him. O'Brien has a determination in his portrayal that reflects the way Bigelow's death sentence has actually made this conviction in him. The transformation from just a normal guy to the hero of this thriller is made entirely believable by O'Brien because he always reminds us in his eyes the fact that Bigelow knows he is going to do die in his eyes which makes it that he is able to have a passion and daring that he would never have had if he had been if this fate had not befallen him. O'Brien is a compelling presence through the story by always keeping the central concept of the story alive in his performance as Bigelow.
O'Brien also deserves credit in the two bookend scenes where Bigelow can finally stop and tell his story to the police. O'Brien properly adjusts his performance here to show that because Bigelow has finally found justice by figuring out his killer that what has happened to him can truly sink in. O'Brien is very affecting as he expresses sadness in Bigelow over his fate particularly due to the rather random nature of why he was killed. There is something very powerful about O'Brien's portrayal of this because he shows that without Bigelow's mission of figuring out who killed him he is only left with his far more somber thoughts that he is doomed man, and his time is just about up.
The only problem I would say with this performance is the limitations put upon him by the film. The film itself really is not nearly as interesting as just the basis for its plot which easily could have made a better film from particularly due to that love story. O'Brien still is solid in these scenes but he just can't find any chemistry with Britton, but to O'Brien's credit he really does try even though there just isn't anything he can do to make these scenes seem more then a waste of time. Even with the limitations though O'Brien's performance is easily the best part of the film. The film could have done more with the brilliant man solving his own murder concept nevertheless O'Brien is very successful in properly humanizes the that concept through his devoted performance.