The book talks about the event written in the Bible. The incident is written towards the end of the Gospel of John. The events take place in time at the stage when Jesus had been crucified and risen from the dead but had not yet ascended to heaven. That is between Easter and Ascension Day. The geographical location of the event is Israel's Galilee, and more precisely on the shore of the Sea of Galilee. Peter was with a few other disciples on the beach and said he was going fishing.
.John tells, among other things, that the exact number of fish in the catch was 153 fish. The Bible does not contain meaningless words or numbers. The number 153 would therefore contain some meaning or metaphor.
The starting point of this book is that the 153 fish contained some meaning, which the readers are trying to find out. We are also trying to find out what was the 154th fish on the coals and its meaning.