The "flash-box" was a device that generated an invisible barrier around the town of Chester's Mill, Maine. The device appeared on Black Ridge on 21 October 2012. Along with generating the Dome, it emitted a band of ersatz radiation that drove animals to suicide, caused visions in humans who passed through it, and glowed at night.
The box was found on the 24th by Joe McClatchey, Benny Drake, and Norrie Calvert using a Geiger counter, and was later examined by Rusty Everett on the 25th. Upon touching the device, Everett experienced a vision of the beings that created the box, as well as reliving a terrible memory from his childhood. He could not, however, move the device or turn it off.
On the evening of the 26th, several more citizens fled to Black Ridge, where they also touched the device. Each saw the beings – which they refered to as "leatherheads" – and relived their worst memories. On the morning of the 28th, Sam Verdreaux, Dale Barbara, Julia Shumway returned to the box, and Shumway successfully pleaded with the beings telepathically to release them.