My standard 120V outlet suddenly went dead, kinda. C/B okay.

My troubleshooting led me to this odd discovery. I pulled the recepticle out thereby leaving only bare wires to test with my voltmeter.

2 black load, 2 white neutral, and ground are in the box. One of the black load wires will read a good solid 120v when I touch the voltmeter to the ground. Oddly, the same black load wire will read only 55-60v when I touch the voltmeter to either of the two neutral white wires.

Subsequently, when the load and neutral are connected to the recepticle, the recepticle reads only 55-60v. What is going on?