A father / son mortician team try to uncover the cause of death on a Jane Doe. The more they uncover, the more mysterious and terrifying their world becomes.

"Uncovering the cause of death on a Jane Doe, a father / son mortician team make their world becoming more and more mysterious and terrifying..."

Until what?

I like it, but just say the more terrifying it becomes. Mystery is implied already with it being A Jane Doe.

'mysterious and terrifying' are too vague.