For a pop series in which coveting treasure invariably leads to certain doom, the prospect of a fifth and supposedly final Indiana Jones movie – with a now 80-year-old Harrison Ford in the lead, and without Steven Spielberg behind the camera – may well constitute one cliffhanger too many; a last lunge for the Holy Grail that brings the whole temple crashing down. Forty-two years after Raiders of the Lost Ark, the series has become as nostalgic for its own blockbuster heyday as its creator George Lucas once was for the serialised adventures of his childhood; the original film's seat-of-its-pants...