After a body is discovered dead in the water it is identified as being Connor Ryan, a 35-year-old male. He was part of the crew of a trawler in a small fishing community. Eve examines the body and Hale explains to her that the rest of the crew are also missing. They soon find out that the boat was originally hired by Wilkes to collect samples for a study of local waters. They all work together to investigate the unusual disappearance of the crew and work out what caused Ryan's death.