On 60 MINUTES: The epidemic of loneliness, a condition more dangerous than smoking; the shocking secrets of a mysterious cult-like church operating in Australia; and our greatest cricketer, the hard-hitting Alyssa Healy.

Liz Hayes investigates the disaster of Boeing's 737 MAX jetliner. Why two supposedly state-of-the-art and safe planes crashed killing 346 people; why pilots now fear flying the 737 MAX; & whether Boeing could have averted the catastrophes.