Many towns let you look up the real estate transaction records online. I don't believe Darien does. Norwalk and Stamford do. In your case, you will probably have to go down to the Town Clerk's office and request the info. (Room 101 of the Town Hall. The hours are 8:30 - 4:30, Monday through Friday. Call 656-7307 for information.) There should be no charge to access the public records. These records are usually available 24 hours after the closing. Online, it often takes 3-4 weeks to be updated.
Hope that helps.