Flash, the spice of Tarbelek, is by far the most valuable spice known in the Par'tha Expanse. Flash is ordinarily black, until exposed to direct light, when it "ripens," turning a glittering gold, sparkling with its chemical conversion. A side effect of this radiation-induced process, if consumed while the spice is discharging, is the effect of a very transient form of telepathy, allowing the user to probe another mind in a cursory manner. Flash has no particularly euphoric effect, although the user can concentrate on absorbing sensations or emotions of the mind being scanned. Tarbelek, the only known source of Flash, is owned by the Valcarian Imperial Republic and mined by condemned criminals, slaves of the Empire.

Nearly all mined Flash is Imperial property, and the vast majority of it is routed to Imperial security agencies and select high-level Imperial officials. A small portion of the rest is auctioned off to select Imperial client states and corporations, who use the spice for the same reasons as the Empire - internal security and espionage, and quiet high-level thrills. At each level, a very small percentage is skimmed from shipments and sold on the black market for incredibly high prices. Even on Tarbelek, a shadow industry of illegal mining skims spice for the black market. A dose of Flash goes for a minimum of 6000 credits.