The Adventure of the Gloria Scott

"The Adventure of the Gloria Scott" which is a part of "The Memoirs of Sherlock Holmes" sends us back to the very first case of Sherlock Holmes.
While Holmes was still a student, he visited an old friend of his, named Trevor. Holmes stayed for a while in Trevor's house but eventually had to return to London. However before he took home, he got to meet one of Trevor's mysterious and strange friends, Hudson. Two months later Trevor died.
What happened? Did Hudson have something to do with Trevor's death? How did Hudson and Trevor meet and what was their past?