Not much to be learned or discovered here. Although, without giving anything away, the identity of the actual killer may be a little troublesome, especially where younger viewers are concerned.
A character is murdered via injection. Needle shown going into arm. Second character murdered, dead body briefly shown. Car goes over a cliff, with an explosion. Guns, shooting at moles in the ground. A little girl falls from a tree house, off screen. Tantrum, with paintings ripped from the wall and stomped on. Arguing.
Kissing. Suggestion of an extramarital affair.
"For Christ's sake," "sadistic pig," etc.
Characters smoke cigarettes and drink somewhat frequently, either alone or in groups. Some overdo it, with hangovers, etc.