As its latest sequel, “28 Years Later: The Bone Temple,” hits theaters (to rave reviews), now is a fine time to catch up with the 2003 zombie flick that started it all — not just this particular franchise but also the entire reimagining of movie zombies. The director Danny Boyle and the screenwriter Alex Garland take a realistic approach to a zombie apocalypse, focusing mostly on the disruptions to daily life, as experienced by Jim (Cillian Murphy), a former bike messenger who awakens in a hospital to find that London is a hollowed-out shell. Shot with maximum immediacy on digital video, it is a harrowing and haunting experience.