Lamberto Bava's "Macabre" is a good slow-burner about a woman who leaves her two young children alone while she's off screwing around on her husband. While in the midst of her sinful intimacy, her oldest daughter drowns the baby in the bathtub. When mommy gets the call, her and the affair frantically speed on home - along the way crashing into a guardrail, decapitating the guy... A year later, the mom is getting out of a mental hospital after suffering from some kind of hysteria after the double-demise on that dark, dark day and goes to stay at the same boarding house where she was cheating on her husband at. The guy living in the house is a blind musical instrument repair man who becomes curious of what the new tenant is keeping in the locked freezer...
I mentioned this movie was a slow-burner and I definitely mean that! However, "Macabre" has an interesting 'build-up' and the pay-off is pretty damn sleazy. Without saying too much, I'll just mention: necrophilia. There. If some early Lamberto Bava is your thing (in fact, it was his first feature length gig), give "Macabre" a watch.