Stop frame animation is used to introduce four bottles of the four blood types. A male narrator explains that there are four groups. Test tubes of blood are shown, having separated into cells and plasma. Another has been mixed with coagulant, clotting the blood. The narrator explains that in a blood transfusion, the patient must receive the correct blood as mixing different groups can result in the red blood cells either coagulating or dissolving, if the match is incorrect. The work of Karl Landsteiner in discovering the four groups is discussed, and the four bottles are seen again: types O, A, B and AB. An animation shows the chemical reaction of antibodies reacting with antigens in the blood. A chart shows what happens if incorrect blood groups are mixed. The narrator explains what antibodies are and what they do, with the aid of animations.