HBO TV film “Nightingale” begins with its troubled hero rambling alone at his home. It looks like a bad thing has just happened, and we feel uneasy as sensing the disturbing tone of his words. Still shaken by what happened, he is angry, morose, and desperate, and he wants to believe that things will be all right for him in the end, though he probably knows that is not true at all.

David Oyelowo plays Peter Snowden, an ex-soldier who has lived with his old mother in her suburban house for years. When he is about to begin his another day as a supermarket employee in the morning, he tries to look fine and normal in his employee clothes, but that does not help him much as he is reminded again of what happened when he and his mother fought over his private matter during last night.

He leaves the house for work as usual. He comes back hours later, and he complains about his work in a video journal for his Internet blog. When others want his mother on the phone, he simply tells them that she is absent or not available. He also does some redecoration job to change the glum, oppressive mood of the house, and he begins to feel a bit better than before.

Above all, he wants to see his old military friend again. For some vague reason, his friend, who is currently married, is out of reach whenever Peter tries to contact with him, but he keeps trying despite being angry and frustrated again and again. He is looking forward to cooking a nice dinner for his buddy, but it becomes more apparent that his friend is not willing to contact with him, let alone accept the dinner invitation.

When he occasionally records his video journal, we gradually gather that Peter wanted something more than friendship from his friend, and that was probably the reason behind Peter’s strained relationship with his mother, who must have been a devout Christian woman considering several noticeable religious items in the house. At one point, he checks a bunch of mails recently sent to his mother, and one of the letters, which was from one of her close friends, suggests that she should be stricter on her problematic son with tough love.

Meanwhile, the situation becomes more difficult for Peter, who begins to show more of disturbing behaviors as being cornered from the outside. He loses his job, and he spends too much money until his credit card reaches to the maximum limit. His lies about his mother’s absence work for a while, but then he gets more phone calls from others. One of her friends actually attempts to get into the house to find out what is really going on, and Peter’s sister also begins to show concern about her mother and her dear brother – especially when an alarming incident is reported on TV.

In its austere minimalistic approach, the movie always sticks to Peter’s disturbed viewpoint throughout its short running time. Its space is limited to the house and a few outside places around it, and there is not any other character in the movie besides Peter and a few extras who are barely glimpsed outside. Even during the phone conversation scenes, we can only see Peter talking with whoever is on the other end of the line, and we can only guess what is being said to him as watching his responses.

While often accentuating his hero’s deluded state of mind through a few visual touches, the director Elliott Lester maintains well the tension silently seething beneath the screen. The movie feels dragged a little as it approaches to its inevitable ending, but its economic narrative is lean and efficient on the whole, and the screenplay by Frederick Mensch wisely lets its character details revealed along the narrative without being overstated.

Of course, the success of the movie depends a lot on its sole actor’s skill and talent, and David Oyelowo delivers a captivating one-man show performance which deservedly received an Emmy nomination. Since his substantial supporting turn in “The Last King of Scotland” (2006), this stage-trained British actor has been an interesting actor to watch as appearing in a number of notable films including “The Help” (2011), “Lincoln” (2012), and “The Butler” (2013), and he recently got his breakthrough moment as Martin Luther King Jr. in “Selma” (2014), for which he should have been Oscar-nominated.

In “Nightingale”, Oyelowo deftly handles his increasingly unstable character as he swings up and down around different moods and nuances, and we come to care about this deeply unhappy man even though his fate has been already sealed from the very beginning. No matter how much Peter tries to get a chance to be happy as before, there is always the hard reality outside the house, and he only finds himself driven to more despair and madness – until he can no longer maintain the delusion he has desperately hung on.

Basically being a storytelling stunt, “Nightingale” bares its rather thin premise at times (the video journal recording scenes feel more like a gimmick for the audiences, for example), but it mostly works as a dark, tense chamber drama, and it is certainly worthwhile to watch how Oyelowo commands the screen in his another impressive performance. Judging from “Selma” and “Nightingale”, I think we will get more good things to watch from him.