Back in the days of three-channel telly in Britain, this was one of the regular sci-fi staples that I really quite enjoyed as I grew up. It features “Messala” himself - Stephen Boyd, only this time he is being placed into a submarine with “Cora” (Raquel Welch) and “Michaels” (Donald Pleasence) and then shrunk. They are to be injected into the bloodstream of a scientist with a view to navigating his internal system, arriving at his brain and the using their laser to zap away a life-threatening blood clot. It appears that miniaturisation itself is no big deal, but after an hour the shrunken object starts to return to it’s normal size. The man they are hoping to assist is the only one who knows how to prolong that period and he had offered his knowledge to Uncle Sam before a car crash instigated by a foreign power had left him comatose. These intrepid travellers can’t be placed directly into his skull, so they are going to have to deal with the body’s formidable defences if they are to have any chance of saving his life. You also don’t have to be Einstein to figure out that one of their number isn’t sailing to the same chart, and it’s fairly obvious whom that is. Of course these are all a trusting team, so will anyone suspect before the mission is sabotaged? None of the acting here amounts to much, but the story offers us the visual effects folks an opportunity to create quite an exciting adventure whilst making our own innards looks distinctly inhospitable; there’s a zapper, some wobbly sets and some treachery too to keep it moving along after an admittedly slow first half hour. It’s not a great film but it has elements of innovation to it and like “This Island Earth” from 1955, it has a place amongst my childhood memories that I will always look upon fondly.