Luke's account of the early church, focusing on the apostles and their deeds spreading the Way (as Christianity is named at this early point). Primarily Peter and Paul are followed, especially Paul at the end on his multiple missionary journeys.
Luke's second book has so many incredible parallels we see to Jesus in Paul's experiences. So encouraging to read of how in all places and all circumstances, Paul gave his testimony - he told his story, and people turned to Jesus and God healed their hearts. We still see this happening today!