Here is the series of catecheses on the Apostles and the Early Church from Pope Benedict XVI. This series follows his Catechesis on Vespers and precedes his Catechesis on the Fathers. It began on March 15, 2006, and concluded on February 14, 2007, and it includes 31 general audiences.
This catechesis is available in book form from Our Sunday Visitor and Ignatius Press. Our Sunday Visitor has also published a corresponding Study Guide which is available for purchase and as a free downloadable .pdf file. OSV has also published an Illustrated Edition of The Apostles.
All of these audiences are available on the Vatican Website under Benedict XVI’s Audiences for 2006 and 2007.