Whatever happened to the twelve apostles? is a well researched book, not only into the history of the twelve apostles, but also other key historical figures from the early days of the church.
The New Testament is surprisingly quiet about the lives of the twelve apostles following Pentecost, perhaps because this information was common knowledge to the early Christians and because they expecting Jesus to return in their life time. So it was not thought necessary to keep records of the missionary journeys of the apostles. Therefore it is a difficult task finding this information. Nevertheless Elva Schroeder has done an amazing job of examining historical documents and books which investigate the lives of the first Christians. She then presents the material in such an easy to read way that even a high school student would be able to understand it.
While much of the evidence is not conclusive the weight of evidence would suggest the conclusions Elva comes to are highly probable.
An informative book which is easy to read.