I think I missed something

Someone help me out here...

In The Doctor of Death Island, the doctor of the title is (I'm pretty sure) Dr. Margotte, the neurosurgeon. He appears a few times, usually in kind of ominous circumstances. In one scene, the usually cool protagonist Alvard just about flips out when a prison guard indicates that he knows Margotte. And he is there again at the end of the story. So it seems he is a really key character. But so far as I can see he never really does anything; none of the action really depends on him. What am I missing?...