In addition to rolling, you also get access to Plot Points. PP let you bend results into your favour. If you really need to hide from those guards, you can spend a Plot Point and roll an extra die toward your total. Maybe that shot coming at you is going to blow right through your brainpan, ending your unseemly career. A few Plot Points may turn that mortal wound into a minor graze.
1 PP = 1 dice step
Example: Wash is doing some tricky flying through significant cloud cover, hoping Serenity can evade a small Alliance gunship. His player decides to spend 3 Plot Points on his next action, so he hands 3 poker chips to the GM and then adds a d6 to his next action roll.
The extra die saves him from a botch, so the GM announces that the gunship is still hot on Serenity’s tail. Wash then decides to pull a rapid deceleration—essentially “putting on the brakes” so the Alliance boat will fly past them. The GM is pleased with Wash’s clever maneuver, and quietly hands the player two Plot Points as a reward.
Plot Points can be spent or saved as you see fit, but* only 6 points can be saved between game sessions*. The rest become Progression Points and are used to improve Skills, Attributes, and either add or remove Traits. Plot Points are the primary reward in the game, and are handed out for good role playing, good ideas, and succeeding in goals. Keep track of your PP.
Plot Points “After the Fact”: You can also spend Plot Points to affect an action after the dice have been rolled. This is generally much more expensive, but can still make a difference on really important actions. Each Plot Point spent improves the die total by only 1.
Example: if the action is requiring an 11 for success, and you roll a 7, you would have to spend 4 PP to get it up to bare minimum.
Plot points in reference to affecting storyline is entirely up to your GM and if they want to enact that rule.