In the prequel to Undercover: Operation Wintersun the events are set in 1938. The smell of World War II is strong and espionage is frequent in Europe. Scientist John Russell is working in a British secret research laboratory, but suddenly he is accused of providing the Germans with secret research materials. With a merry and faithful Audrey, secretary of the research institute's director, he only has 24 hours to find the actual spy and to prove his innocence before it is too late!
There are two playable characters, Russell and Audrey. Players can select and switch between them on both screens of the DS at any time, directing them in 3rd-person view via the touchscreen and stylus. The 1st-person view is used to solve the logical puzzles and compete in 10 mini-games including darts, boxing, and more. It can also be applied to make use of the individual abilities of the characters to perform an investigation.