Franklin W. Dixon 
Cold Cash Caper [EPUB ebook] 

The Hardys look to put a gang of armed robbers on ice!Frank and Joe have volunteered to do undercover security work at the Bayport winter festival. Their main assignment is to act as bodyguards for the star performer, Olympic gold medal figure skater David Kennedy. Although put on for a good causecharitythe festival is soon plagued by bad vibes: Money intended for the local childrens hospital is ending up in the hands of masked, gun-wielding thugs, and its up to the Hardys to stop the robbers cold.