A special formula has been developed which enhances the performance of athletes. However, no-one has considered the after effects, which are that when the person's heart reaches a certain rate, the body can't cope and the person drops down dead. Ed comes to realise this when he is having a karate match with a person who has been injected with the stuff, and the man goes hyper, then falls down dead (whoops!). Ros eventually goes to find out more about the stuff, and ends up with another hyper person chasing her, then he suddenly collapses. however, Ros is still caught and taken away by the developer of the formula, to be his new guinea-pig. (thetvdb.com)