Complex sentence: McQuarrie was introduced to the project while directing Cruise in "Jack Reacher", and while reading the earlier script he "understood very clearly what the premise of the story was and what they were looking for in terms of characters".
Split into simpler sentences: McQuarrie was introduced to the project while directing Cruise in "Jack Reacher". While reading the earlier script, McQuarrie "understood very clearly what the premise of the story was and what they were looking for in terms of characters".