Unforgotten Guest cast, played by Daniel Flynn Episode 4x01: Episode 1 (Feb 22, 2021) Episode 4x02: Episode 2 (Mar 1, 2021) Episode 4x03: Episode 3 (Mar 9, 2021) Episode 4x04: Episode 4 (Mar 15, 2021) Episode 4x05: Episode 5 (Mar 22, 2021) Episode 4x06: Episode 6 (Mar 29, 2021)