Go up above the Bastille to reach the Petit Bastille. On the very right hand edge of the roadcut (while facing South), you will see a tiny curved dihedral that leads up the East side of the arete to cracks on the arete on the West side. Climb up to and through this dihedral protecting with a few small nuts and maybe a tiny cam. A crack appears on the right for more of the same pro. Pull up and right on thin cracks to the arete and to the cracks on both sides of it, following the thin wall upward to eventually gain the top of the rock. When the rock slopes back up top, continue maybe 5 meters over the edge to a bomb-proof belay seat and good gear.
There is some poor rock and poor pro down low, but the moves are really quite good. 1 star overall.
To descend, walk up the ridge to the South, then down the West end. This is MUCH better than the way off to the east.
A standard light rack with some longer slings. The crux sections protect on iffy small nuts and small cams. The route would be dangerous to lead at one's limit.