Forest Whitaker threw himself so deep into his role as former Ugandan dictator Idi Amin in movie The Last King of Scotland that even his wife and children refused to talk to him.
The actor devoted himself entirely to the part, for fear failure might put an end to his burgeoning career.
Disciplined Whitaker stayed in character off set, ate only mashed bananas and beans, and learned the languages of Swahili and Kakwa.
But director Kevin MacDonald insists the unusual lengths he went to paid off.
He says: "Having done mostly documentaries until now, I didn't know much about actors. This was method acting taken to extremes and I watched with astonishment.
"Forest was at a crisis point in his career and this felt like make or break. For nearly six months he wanted to be Amin, not just perform him.
"But in the end I could see there was method in the madness - he acted at the top of his game."