Louche, long-haired and loose-limbed, John Paul Getty III (Charlie Plummer), unhurried and expectant, drifts through Rome’s Piazza Navona on an early morning in 1973.Sex, drugs and radical politics collide in the city’s hip club scene, and 16-year-old “Paul” is one of its familiar denizens.As prostitutes taunt him to go home to his mother, a van screeches into the plaza. Its unseen inhabitants call out to him then snatch him, taking him for the ride of his life.“All the Money in the World …