So, the story is basically this - set in the late 19th or early 20th century, a man suffers a head trauma and is left unable to see normally. Instead of being able to see the things around him, he instead sees events surrounding a Royal Naval expedition to some islands on the other side of the world, as if he were seeing them from his own view point.
If he moved around, his view point on the island also moved around - at one point he is walked down some stairs and his view takes him under the sea. It is determined that what he sees is actually historical in nature after he identifies several things about the expedition which are corroborated.
He cannot hear any noise associated with the view, so he is able to communicate normally with his friends.
After a period of time, the view of the island starts to deteriorate and he regains his normal sight.