[AndrewO]

Or, if the masters are too hard at first, see if their pupils have written annotations. I tried Turing, couldn't even understand why what he was talking about was important (or why his "computers" seem so much... lamer than the ones I was used to), and then found Charles Petzold's "Annotated Turing".

http://www.charlespetzold.com/AnnotatedTuring/

He takes Turing's "On Computable Numbers..." and mixes in chapters giving the necessary background on the history of mathematics, number theory, logic, etc. in-line (albeit, it takes about 100 pages to get to the first sentence of Turing's paper). I whole-heartedly recommend it.

[nonviable]

Another vote for The Annotated Turing. Really does a great job of shedding light on a rather esoteric paper.