From Charlize Theron and David Fincher, 'Mindhunter' delves into the darker corners of the criminal mind

To meet Jonathan Groff and Holt McCallany, stars of the Netflix series “Mindhunter,” you’d never suspect they recently spent 10 long months consumed with the darkest reaches of the human psyche.

Groff, a charmer known for playing the lead in HBO’s “Looking” and King George in the original Broadway...