“Happy Face,” streaming its first two episodes Thursday on Paramount+, only sounds positively upbeat.

For the smiley insignia here is the mark of notorious Happy Face serial killer Keith Hunter Jesperson.

The series, inspired by the podcast and memoir of Jesperson’s daughter Melissa Moore, stars Annaleigh Ashford, 39, as Melissa and Dennis Quaid, 70, as Jesperson.

For the Tony-winning Broadway veteran (“Sweeney Todd”), Melissa was an irresistible challenge.

“A good story and good character has conflict,” she said in a Zoom interview, “and when you are playing the daughter of a serial killer, it’s just conflict abounding!

“Not only in our fictionalized version of this story but in real life. There is a constant moral conflict in being related to somebody who committed heinous crimes.

“If you have a family member who committed an act of crime this serious, it would not only change the way that you look at the world and your family — it would change the way that you look at yourself.

“Is this nature? Nurture? Is this part of me? Will it be a part of my children, my grandchildren? Or was it just him?

“That is a complicated question — and so interesting as an actor to play.”

When Melissa was celebrating her 15th birthday, she had life-altering personal news – and then the police arrived and arrested her beloved father. Overnight, he went from doting dad to monster.

As Ashford said, “You can’t make this up! If it were fiction no one would believe you.”

How is Melissa unique?

“While she is having to navigate coming out as the daughter of a serial killer — and the embarrassment, shame and guilt that comes with that, and what her future is like, what it looks like for her family, her children — I was really struck by real life Melissa.

“When she did come out as the daughter of a serial killer” – on “Dr. Phil” – “she used that bad act to try to make good.

“To use it as an act of service for the victims’ families, and for other families who are the victim of true crime.

“She has a real gift for empathy and an open heart — just so the opposite of her father. I truly tried to live in that space of her spirit and show how her goal was to make things right. That is such a worthy objective.

“And on a lighter note I just tried to make the crew laugh as much as possible. Because when you’re doing heartbreaking content, you need to make sure that everybody has some laughs. And some good snacks.”

Paramount+ streams 2 episodes of “Happy Face” on March 20