When Toby has to go into hospital for a check-up, he is worried not only by the thought of X-rays and blood tests but by the strange atmosphere there. His room-mate Jacob tells him about a boy called Nick who had suddenly been taken ill just before leaving hospital. Then the same thing happens to Jacob the day before he is supposed to be going home. Jacob is taken away and put in another room. Toby does not like the head of the hospital, Professor Hazlitt. There is something very strange about this doctor! A month earlier, two children had died in this same hospital! Will Nick and Jacob be the next to die? What on earth is going on?