As an ex Merchant Seaman I was really interested in this movie : I personally have been involved in a stowaway search on leaving Kingston Jamaica where one person was found. We managed to get him ashore though as we were in territorial limits. On another ship I was on the stowaway was found and we could not land him anywhere due to passport/nationality issues. In fact he stayed on for a year as an almost "honorary" crew member and worked for his keep. Africa is notorious for stowaway pickups. There is a great scene in the beginning of the film when the bulk carrier enters the African port : her size dwarfing all. The crew pop ashore for a little intercourse and inebriation. So far normal. The drama starts when the stowaways enter the vast cavernous holds of the ship. Joss Ackland is brilliant as the Captain with a drink problem being harassed by his Nemesis Suchet right on form as the Companys representative on board. The stowaway search is classic but we did not have guns. I question the use of guns in this film. This ship seemed to have a vast armoury. In my experience guns at sea are severely restricted due to customs regulations., also having a dog on board was odd.Anti Rabies laws especially in Europe restrict carrying of animal severely. Anyway Pertwee is brilliant as the embittered Mate. The horror which follows the discovery of the victims is unbearable : the grim metallic background of the ships holds and a feeling that there is no where to hide adds to the drama.Some of the freighters crew are not into the murder and those who get involved are gradually sucked in to a world of violence from which there is no escape.The chase through the ship especially the engine room scenes are "edge on the seat" : the feeling of extreme claustrophobia abounds. The feeling of metal pressing in and death being only a gun barrel away. The film is brutal : my girlfriend had to give up watching it during the shooting and beating scenes. While this goes on Suchet in the comfort of his well appointed cabin gets drunk unaware of the mayhem 3 decks below. Its a tense film, flawed in parts but the real message is that we can all get sucked into violence like this. Slowly and surely. Think of the train drivers who took Jews to Auschwitz, the clerks who worked out those train timetable. I always remember someone who had visited Dachau concentration camp at the end of the war and he said that one of the S.S. Guards had put a bird-table outside the camp crematorium. This film is like that : ordinary people suddenly finding themselves in a world of unstoppable violence!