Flashbacks: Henry and Trish were dating 7 years ago. The burned guy, Cole, was burned in the dock explosion. Abby witnessed one of the murders and found the bodies. Jimmy saved Abby's life. Wakefield was involved with Abby's mother and Mills had him sent to prison. The flashbacks mostly weren't great but the events surrounding the murders were interesting.
After all the effort Malcolm went to to hide the money, Sully finds it because of a joke. Malcolm burning the money was a nice gesture, after all the misery it's caused. It's a little sad that after that, the killer kills him. The same thing will happen as when Booth disappeared, they'll think he took off with the money.