HBO’s The Inventor: Out for Blood in Silicon Valley is an excellent film is about a defunct biotech start-up, Theranos, and founder Elizabeth Holmes.

Her company, its peak valued at $9 billion, promised investors a device, the Edison, that could diagnose nearly 200 conditions through a pinprick of blood.

The prototype turned out to be inoperative bunkum, but here’s the question: Was Holmes trying to pull off a con or bluffing until she worked out the kinks?

The documentary, directed by Oscar winner Alex Gibney (Taxi to the Dark Side, Going Clear: Scientology and the Prison of Belief), airs on HBO March 19 at 9 p.m.