Just give the inmate a roofie and have him wake up in an all white room, with a white door, and a "window" that isn't actually a window but looks like one and it looks like snow is covering everything outside. Bright fluorescent lighting. The guards wear all white outfits that cover them from head to toe. On the inmate's white table is a red pill and a blue pill, with a note that says "follow the white rabbit." Both pills are a lethal dose of cyanide, but the inmate doesn't know that.