While on a case, Oliver and Shane enter a bank vault, where they discover a life-changing treasure. However, they soon realize they're trapped in the vault with little oxygen. Meanwhile, Rita reaches the state level of the Miss Special Delivery contest.
The postal detectives search for a singer-songwriter using the lyrics from his undiscovered song, which leads them to learn the details of a fated evening. Meanwhile, Shane's old pal arrives and causes a commotion at work.
A letter postmarked with a future date arrives and leads the postal detectives down an unexpected path. Meanwhile, Rita is bullied by an aggressive supervisor whose daughter is competing against Rita in the Miss Special Delivery Pageant.
The postal detectives try to deliver a package from a son to his estranged dad. Meanwhile, Cora becomes captivated by Rita's novel and imagines living in the Wild West; and Shane and Oliver grow closer.
The gang head to a ranch to try to deliver a potentially life-changing love letter. Meanwhile, a new boss sets some stern guidelines for the team to follow; Oliver and Shane bond on the dance floor; and Rita pursues her dream of writing a novel.
An error sends a new employee to the Dead Letter Office, where she encounters an eccentric staff of mail detectives who attempt to deliver every piece of misdirected mail. Before long, the new employee finds herself moved by one particular love letter.