Not sure which wire you mean? The high-voltage main coil lead to the distributor center terminal is just out of frame at the right edge (you can see some of the boot on it there). The hose with blue and black/white wires coming out of it from top-left is from the ICM inside the distributor. The blue booted terminal at lower-left is one of the black/white wires, which all connect to that end of the ballast.

The white wire goes to the tach. The black/red wire (with the burnt-looking terminal on it here) goes to one end of the ballast resistor, which also has a black jumper wire to the (+) terminal on the coil. That leaves one more set of blue and black wires from the noise-suppressing condenser (little black box visible just above the ballast), where the black goes to a ground, and the blue wire goes to the same ballast terminal with the black/white wires.

Note this is an aftermarket Herko B108 coil, and I dis/reassembled the mounting bracket to flip the coil around for easier wire routing. Not sure if a stock coil would have the coil +/- terminals oriented the same way, so check for any markings on yours.