A screenwriter Hee-jin (played by Choi Yeo-jin) goes to the Philippines with the director (played by Ryu Seung-su) to collect information for a film featuring diving. One of the interviewees named Si-eon (played by Jung Chae-yull) recalls old memory the moment she sees Hee-jin. Hee-jin had learned yoga from Si-eon, who used to be a yoga instructor. They became friends and learned diving together. They used to be close but something went wrong. The director notices a strange vibe between Hee-jin and Si-eon, and soon becomes interested in a shocking relationship in which the two are involved in. ‘Deep’ diving means going underwater to 60 meters or deeper. Using this as a metaphor, Deep takes this film to a story about a relationship that develops ‘deeper.’ What happens on the surface is completely different from what happens below the surface. The same goes to a human relationship; nothing is as it seems. It may look like ordinary love or friendship on the surface, but there exist deadly relationships and plots under the water. A person’s capability is said to determine how deep he can dive underwater. Watching Deep , the audience may wonder the depth of a human relationship can be compared to that of diving. (HUH Nam-woong)