Danny Boyle’s “28 Days Later” is a great example of a film that keeps its focus for its first two acts, but loses itself in a conclusion on autopilot.

Jim (Cillian Murphy) is a young Brit who wakes up from a coma to find London a deserted wasteland. He learns, in a series of absolutely astonishing shots, the majority of the world’s population has been wiped out by a blood-borne virus that infects its victims with a murderous rage, turning them into blood-hungry zombies.

Jim is saved by two uninfected people — Selena (Naomie Harris) and Mark (Noah Huntley). The two inform him of the harsh realities: Stay out of the dark. Never move alone. Kill or be killed.

After a series of attacks, Jim and his small band of survivors head for Manchester, where they are promised refuge from the savage zombies.

The film is handled with expert touches in bits and pieces. The character development, for one, is a welcome presence. I found myself caring about these people and the situation they were in.

The questions “28 Days Later” poses are scarier than the film itself. Despite a sour conclusion — and I do mean sour — the film still rises above the pathetic, needless retread of explosions and car chases.

Despite a sometimes-heavy lean on Richard Matheson’s “I am Legend,” “28 Days Later” contains few clich‚s. The moments of suspense and quick scares occur unexpectedly and there is no cheesy love story between the two stars.

The film reminds me of last December’s “Solaris,” a film similar in nature.

A major question posed is why these characters don’t just put themselves out of their own miseries? In an impossible circumstance, such as this, why would you even try to attempt to put up a fight?

Zombies or no zombies, what would you do with yourself if you were one of the last people alive? Would you be more paranoid of your surroundings? More mindful of a small noise in the back room? Still nervous that someone may see you undressing in front of a window?

Flaws, both major and minor, “28 Days Later” is the thinking person’s horror show. If one is patient enough, a lot of the film’s shortcomings can be forgotten in reflection of the film’s ambitious attempt .

“28 Days Later” doesn’t scare me, but rather keeps me at the edge of my seat. This rare experience of actually being in suspense is a welcoming feeling. Although it’s far from the best thriller, it deserves a place in a short list of nail-biters that hold interest while simultaneously keeping a mindful eye on its story.