The Acts of the Apostles is a book of the Bible, which now stands fifth in the New Testament. Acts tells the story of the Early Christian church, with particular emphasis on the ministry of the Twelve Apostles and of Paul of Tarsus. The early chapters, set in Jerusalem, discuss Jesus's Resurrection, his Ascension, the coming of the Holy Spirit on the Day of Pentecost, how God added disciples to the Christ's church, and the start of the Twelve Apostles' ministry. The later chapters discuss Paul's conversion, his ministry, and finally his arrest and imprisonment and trip to Rome.
(Summary from Wikipedia and Sam Stinson)