Complex sentence: Mason contacts O'Malley, who comes over with some weapons for him, and tells him that his son is still alive-O'Malley took Mason's son in and raised him, sending him to a private school so that he would be out of danger.
Split into simpler sentences: Mason contacts O'Malley, who comes over with some weapons for Mason. O'Malley tells Mason that his son is still alive-O'Malley took Mason's son in and raised him, sending him to a private school so that he would be out of danger.