First of the GUMSHOE system RPG's where, unlike other systems, this helps the characters get the first clues but then have to use their skills to uncover more.
The idea is the system helps to drive the plot along rather than totally rely on the players ability to deduce or get that luck roll.
Really well thought out, simple to learn/teach system that is expanded upon in the other games in the series as well as expansions for this.
Excellent system well worth a look