Asterix and the Black Gold, Paperback/Rene Goscinny

Without the powerful potion whipped up by the Druid Getafix, Asterix and his fellow villagers would never have the strength to fight Caesar's legions. Now Getafix has run short of rock oil, an essential ingredient in the concoction. There's nothing left to do but have Asterix and Obelix prospect for black gold in the Middle Eastern desert. But the Roman secret agent, Dubbelosix, using his amazing folding chariot and new spy gadgets, is determined to stop them.