One of the things that is the most boring in a film is when something just happens. The hero mysteriously finds the clue he's looking for. He stumbles across a gun that is in the plain open. He hasn't had to WORK for anything.
Part of a great script is watching the hero's journey, and your hero's journey NEEDS to be fierce and treacherous. We NEED to feel the highs and lows with him/her. We HAVE to BELIEVE that everything that promotes him/her comes at a price. He/she needs to earn every bit of info, every weapon, every THING that he needs to fulfill his quest. We are traveling with him/her. We need to go with the hero to every gun runner, every crime spot, etc.
If you want to go on a great journey I suggest watching CHINATOWN with Jack Nicholson. Robert Towne did a masterful job of writing, and Roman Polanski, who directed, only added brilliance by removing all voice overs by the character, Jake Gittes, stating he (Polanski) wanted the audience to discover the clues as Jake found them. It worked. I mean, an Academy Award won't lie, right?