Neal and Peter are still at odds with each other, as Neal and Mozzie attempt to snag the Nazi submarine's manifest before it gets to Art Crimes division and Agent Melissa Matthews.
Meanwhile investigative journalist/editor in chief Helen Anderson is receiving death threats. Diana is placed undercover as Helen's new executive assistant, and she doesn't enjoy her new role as journalist flunky.
Peter and Neal take a look at Helen's case and discover the culprit is a pharmaceutical company which Helen had been looking into. One of the company's drugs may be responsible for the deaths of many patients, and the company may be covering these incidents up.
Peter requests that Diana translate some of the U-Boat's manifest to see whether any of the items listed were sold illegally. However, Neal gets Diana to agree to a double-date dinner party with their respective loved ones in order to get into Diana's house and steal the list.