Nigel Messenger provides a fine introduction to the fiction of E. M. Forster. The book is basically aimed at people who deal with the author as students (which may distract non-academic reader) but the amount of information provided is so big, and the information so interesting that it is worth to look into the book. Anyway, if you get stuck on the fifth page of Where Angels Fear to Tread and you do not know what it all is about Nigel Messenger is the person to ask. If you have to write a five pages (typewritten!) essay on E. M. Forster - you simply must buy the book. The only problem may be that your teacher was a bit quicker so mark your quotations!