Craig Evans has written an article on Morton Smith and Secret Mark. Let this concluding paragraph wet your appetite to read more:
“No, I have not proven that Smith fabricated the letter of Clement, along with its quotations of Secret Mark, but I do not see how critical scholars can make use of such a text and still call their work critical and scholarly. Scholars interested in the early history of the Gospel of Mark, the historical Jesus and his understanding of the kingdom of God, and critical issues debated by Clement and other Christians in the late second and early third centuries are well advised to make no use of the Mar Saba Clementine.”
the archives near Emmaus 
I shared some thoughts on Evans’ article on my blog which you may or may not find interesting.