As NCIS mourns the loss of Ducky, the agents find comfort in working on one of his unfinished cases involving a woman whose father was dishonorably discharged from the Marines.
When the NCIS team engages in Walk-a-Mile day to gain a new perspectives on different departments, things take a turn when Kasie receives a distress call from a mysterious man.
Parker and Knight discover three bodies on an old Navy ship that's about to be sunk and turned into an artificial reef, when they're suddenly locked inside by a mysterious figure.