What to read after In the Dark?

In the Dark Edith Nesbit - What would you do if you realized your close friend was getting mad? Your bosom-friend you know the whole life. I guess, you would try to help him like I did. But what if you faced with supernatural? I suppose that you'll be able to help me to solve this puzzle. And we will find the truth. Let's start from the beginning. When we were studying at school with my friend, there was one boy. He was a sneak. He always told the teachers wrong things other children did. But he didn't see these bad deeds with his own eyes. He just knew everything and the teachers believed him. I don't know what it was. Was it a third eye or a sixth sense? It is unknown. I don't know much about these things. But I believe in common sense. After graduating the university, I went to another country. All the three of us chose different ways in life. Time passed. After my arriving in London our paths crossed in a very unusual manner.