From what I know, when the attack happened there were protests in several countries about a really nasty anti-islamic movie that had gotten put online. There was some confusion at the time if the attack in Benghazi was one of the protests, or if it was a planned terrorist attack that used it as cover. The State Department was trying to give reporters what they knew at the time, which of course changed as they were getting new reports from the CIA.
Now for the 'scandal' part. That the official story that was put out changed was Obviously a sign the White House, or Hillary, was covering up something. The conspiracy stories then started to get more bizarre, like claiming the military had people that could have gotten there in time to help (they didn't) but the White House told them to stand down. Not sure what other theories have been floated. I do remember one Republican congressman at one of the hearings saying they could have gotten help from the secret CIA safehouse that was nearby, pointing out the SECRET CIA facility on a map.
The investigations have resulted in as much real scandal as Whitewater. In other words, nothing, but they need a scandal to campaign and fundraise on, so the investigation continues.