It's the start of a new week for the team of intrepid postal detectives tasked with tracking down the recipients of undeliverable mail. Amongst the hustle and bustle of shuffling letters, Oliver O'Toole (Eric Mabius), the rigid leader of the team, makes his way to the office. As he moves through the mailroom, he bumps into department newcomer and resident technophile Shane McInerney (Kristin Booth). As Oliver and Shane arrive at the dead letter office they are greeted by the free-spirited, "girl next door" Rita Haywith (Crystal Lowe) and the nerdy but lovable Norman Dorman (Geoff Gustafson). It's a particularly special day at for the dead letter team as they prepare to welcome their new supervisor, the legendary Theresa Capodiamonte (Valerie Harper)!

The postal detectives track clues to deliver a love letter that can change lives, while their strict new supervisor is on a journey of her own.