Nigeria sits atop 25 billion barrels of high-quality crude. But extracting the oil from the swamps of the Nigerian government can be messy. Nigeria ranks second (after Bangladesh) among the world's most corrupt countries, says Transparency International in Berlin. Cozy ties between oil multinationals and the government (a partner in all ventures via the state-owned Nigerian National Petroleum Corp., or NNPC) make evidence of mischief hard to find. Until a deal goes sour--and the ugly process spills into view.