Does whale watching protect or harm whales? This film explores heated controversies over whale watching, boat noise, and orca conservation in Washington State and British Columbia. Whale watching companies claim that they serve as "sentinels" protecting the orca from unwary recreational boaters, ferries, and ships. A number of local conservationists and scientists have argued that whale watching boats crowd and harass whales, while adding noise to the orcas' immediate environment that makes it difficult for the social species to survive. "Sentinels of Silence?" uses dramatic imagery, peer-reviewed science, and interviews with conservationists, scientists, and industry officials to bring a fascinating chapter in the orca conservation story to light.