This episode involves good acting and solid characters. But that's it, as far as I am concerned, with the positive aspects of this episode.
The first thing, that really annoyed me, was the presence of Charlie at the first crimescene; what is he doing there? He's a consultant for the NSA and for the FBI, but why is he checking out the crimescene of a seemingly regular car-accident from the start. If there had been any mentioned circumstances in the plot, that had suggested the need of a mathematician, I would understand, but there were none... He's of professor for math after all and thus not supposed to be at all crime-scenes, his brother Don is at. I don't recall Charlie switching to policework fulltime.
So Charlie clings onto this accident like he already knows, there's something wrong with the accident beeing one and surely detects an 'anomoly' (the final scene includes this misspelling by Charlie, a scene which I really liked). From there the story goes on in a fairly logic plot. 'Fairly' because of the weak spots, that annoyed me: like the witness' whereabout beeing noted somewhere in the police-computer-system, which is very unlikely. Second it is never fully revealed, how the two vehicles, that caused the accident were coordinated, so that an actual accident resulted from their behavior. They had to be just in the right place at the right time which still wouldn't have been enough, as the key to the accident was the reaction of the busdriver. If he had reacted slightly different, the accident perhaps would have never happened. How could the people, that organised the accident, have incorporated his behavior? Not if You ask me and that's the way most of the key-points of this story work. To much coincidence for me...
After all I enjoyed watching this episode, but more because of the characters but because of that implausible story. If a good script is Your main concern for the quality of an episode, this one is not for You.