Killer Instinct

Three months ago, four kids were run off the road by a drunk driver and pronounced dead at the scene, leaving their families to grieve and wonder why accidents had to happen.
The four left behind families, and namely, five specific siblings: all seniors in high school but not all similar. The five don't interact too often, but a common thought brings them together: what if their siblings had been murdered?
As they begin to work together to find out who killed their older siblings, the five begin to realize that they might be getting in over their heads--for the four families have secrets that intertwine them beyond what anyone could have imagined, and the five teens find themselves in possession of the very secrets that may have got their siblings killed in the first place.