At an exclusive auction house in New York City, Vincent van Goghs Sunflowers, which was believed to be destroyed by a US air raid of World War II, was put up for auction. Jirokichi Suzuki, accompanied by his niece, Sonoko won the auction with a $300 million bid. At a press conference, Suzuki announces his plan to gather all seven Van Goghs Sunflowers paintings around the world for a grand exhibition. The venue would be a purpose-built gallery in a cliff in Japan known as Lake Rock, with the highest security and protection. Suzuki also announces the engagement of seven specialists, whom he called the Seven Samurai, to oversee the exhibition and protect the Sunflowers.

Conan then tries to track down Kaito Kid, who supposedly steals a one of Van Goghs Sunflowers paintings during an auction.

(Source: Wikipedia, TVtropes)