A federal appeals court has blocked a reward of more than $10 million (pdf) for a Venezuelan man who helped Peru capture a notorious spymaster in a tantalizing case that the panel said “read like the latest spy thriller.”

The 11th U.S. Circuit Court of Appeals issued a 2-1 ruling Friday reversing a judge’s decision that Jose Guevara should get the $5 million reward plus at least $5 million interest. The ruling concluded that Peru was shielded by U.S. laws that protect sovereign governments from lawsuits.