If you found 2001: A Space Odyssey (1968) baffling then you'll find this sequel rather more entertaining mainly because it's a fairly straight forward genre piece with a good solid story and specifically adapted from it's source novel by director Peter Hyams. Roy Scheider plays Dr Heywood Floyd (a relatively minor character in the first film) who has been forced out of his job due to the failure of the 'Discovery' mission to Jupiter. But he is enticed back as part of the crew of a joint USA & USSR mission to find out what happened on the first mission. The result is a captivating sci-fi story with some great visual effects, a side plot involving international tensions back of Earth and elements of Kubrick's original surrealist plot. With Helen Mirren, in her first American film, and John Lithgow as co stars this is well worth checking out even if you didn't really get the first film. This one sort of helps explain the basics . But that aside this film often gets unfairly compared to Kubrick's classic but that's a mistake because this is a completely different style of film from a director who focused on the great novel by Arthur C. Clarke. Well worth seeking out if you have never seen it.