This Longform story, Eat What You Kill, is astonishing and well worth your time. At the heart of it is a doctor growing rich by misdiagnosing patients, including one who died after receiving chemo for 11 years for stage 4 cancer despite never having cancer:
Hailed as a savior upon his arrival in Helena, Dr. Thomas C. Weiner became a favorite of patients and his hospital’s highest earner. As the myth surrounding the high-profile oncologist grew, so did the trail of patient harm and suspicious deaths.
You can read the full investigation on ProPublica: Eat What You Kill by J. David McSwane.
I'll point out that ProPublica is the best place for thorough journalism that I'm aware of. When I cancelled my subscriptions to The Guardian (due to anti-Trans bias) and The Atlantic (too expensive), I funnelled that money into a monthly donation to PP.
Another banger piece they published just this week was The Militia And the Mole by Joshua Kaplan:
A wilderness survival trainer spent years undercover, climbing the ranks of right-wing militias. He didn’t tell police or the FBI. He didn’t tell his family or friends.
He only told Joshua Kaplan at ProPublica.