A long overdue book. Copeland collects together Turing's greatest papers. As in where Turing tackled the fundamentals of what is now called a Turing machine - ie. a universal computer. Plus other papers where Turing ruminated on artificial intelligence, and founded that field. Plus coming up with the Turing Test for AI.
Turing's papers are interleaved with chapters by Copeland that give extra context to the times in which Turing lived. Notably on Turing's crucial contribution to the Enigma project at Bletchley Park during World War 2. It is no exaggeration to say that his insight into decoding the German encryptions saved the lives of thousands of Allied soldiers.
Valuable also is a reprinting of Turing's "Treatise on the Enigma", which was only declassified in 1996. Though by then, its essence had been known for decades. Finally, the book lets you read Turing's words on Enigma.