The Book of Acts, also known as Acts of the Apostles, is the writing in the Bible (or accumulated Scriptures accepted by most Christian denominations) that is a continuation of Luke's Gospel, but the book can be found in scriptures after the book or Gospel of Saint John, also known as the Beloved, but before all of the letters or Epistles of the Apostles or Saints. Gospel means "good news." Luke was a physician and companion of the Apostle Paul. The Acts of the Apostles is the story of the disciples of Jesus Christ of Nazareth after His death and resurrection, and their missionary work. It is unusual in that it changes 'person' grammatically in its context.
The coming of the Holy Spirit as a baptizer, and the Apostleship of Saul (now Saint Paul} of Tarsus are the main elements in this chronology. Saul was behind the zealous Jews' persecution of Christians (where we learn the first ones called that were in Antioch, Syria, but on his way back from Damascus, with more paperwork to seal Christians' fate, he was knocked off his horse by a resurrected Jesus, who convinced him, "It is hard to kick against the thorns" and he became called, even though he was a Pharisaic student of Gamaliel, to bring this Good News to the non-Jewish, non-believing world.
Here we are introduced to the first Christian martyr, Saint Stephen. He was ordained as one of the first deacons (kind of a combination, collector, usher, and or waiters) of the church, but wound up preaching the whole history of Israel, up to the present situation of his audience's guilt in crucifying his Lord Jesus, and he wound up stoned to death for his direct rebuke. Interestingly at this time future Apostle to the Gentiles, Paul, was standing by approving of this action, thus why he always called himself "chief sinner."
Pentecostal, and charismatic Churches use the "Day of Pentecost" in this book as proof text for the same Holy Spirit Baptizing today, with its evidence of speaking in tongues.
The journeys of the Apostle Paul, being beaten, shipwrecked and jailed almost rivals those of another ancient written about in Greek, Ulysses. This time the protagonists wind up in the biggest capital in the world at that time, Rome.