The most intriguing idea contained in this book is that, as Bockmuehl argues, we may not be able to know exactly who Peter was or what he actually did, but we can note his importance and the degree of influence that he held over the early church by the shadow that he casts, the the ripples that he left in his wake. Bockmuehl the examines what those ripples would be, even as he admits that some of the literature about him may not be wholly accurate. It's a good point. Why, after all, would so many early writers fuss over Peter or try to tie their own claims to Peter were it not that Peter had some kind of heavy early influence. He must have been an important apostle.
Bockmuehl does this by examining first writings left behind in the Eastern church and then in the Western. As he notes, few in the Eastern church lay claim to him as one of their own, that is, as one who traveled extensively in the area. Rather, Peter is more often associated with the West, even in the East. And his martydom in Rome is acknowledged by quite a few early writers—hinted at if not outright stated. Bockmuehl also provides a useful website where he summarizes, or gives quotes from, the various early writings about Peter, which should be very useful to anyone else who might want to examine the evidence.
He closes his book by looking at Peter in two particular situations. First, he looks at Peter's conversion—or rather the narrative of it. Much attention is given to Paul's conversion on the road to Damascus, but we have no similar single moment provided for for Peter. Yet in Luke, Jesus tells Peter that he will be handed off to Satan for a while, and when he returns, he should take care to care for others. We never really see that moment. When did it happen? It seems to have occurred between the end of Luke and the start of Acts, wherein Peter is already strong in the faith. Bockmuehl guesses that the turn to Satan happened at Peter's denying of Jesus, which would make sense. The turn back would happen at Jesus's resurrection, when Peter saw Jesus, which would also make sense. John's recounting of Jesus telling Peter to “feed my sheep” three times works off this theme of conversion—insofar as it's the opposite of Peter's three-time denial.
Second, Bockmuehl looks at Peter's upbringing in Bethsaida, which is only mentioned once in Scripture. This was perhaps the most interesting reading Bockmuehl did in the work. We associate Peter with Capernaum, where he lived as an adult. Bethsaida was a far different area—mostly, from what we can tell, Gentile. As such, Peter would have been quite familiar with non-Jewish culture and likely would have spoken Greek (contrary to what many try to argue—namely that he didn't know the language), even though he likely grew up in a devout Jewish household. Such a background, of course, would have made Peter a very useful apostle indeed.