Yesterday evening the car ran fine. This morning I put key in ignition and get normal chimes, etc. Turn the ignition and suddenly nothing. Horn, gauges, are completely dead. Trunk light does work.

Battery is fully charged. Cables are tight. From the behavior I assume it is a (master) fuse of some sort.

Any ideas?

 

Suggest removing and cleaning each battery cable first to be sure there's not some corrosion in the clamp preventing current flow. Check starter and ground connections also. If those are good, trace voltage to the underhood fuse box fuses and onwards. Somewhere there's a bad fuse or loose connection.

It's also possible that ignition switch assy has gone out. I've never head of one failing quite so completely at once, but it may be possible. If all battery wires, fuses check out, then ignition switch seems likely.

good luck