Cold Case Summer is the ninth game in the long-running series of first-person adventure games from developer MDNA games. This is a point-and-click adventure game that involves exploring for clues and inventory items, as well as solving logic and inventory-based puzzles. The game's artwork is made from still photographs taken in Sweden, with node-based movement. As with previous games in the series, there is voice acting and background music. There is a new hotspot revealer making it somewhat easier to locate items of interest.

During a particularly sunny August evening, Carol is approached by a mysterious man who wants her help. Carol declines, since the man doesn’t want to reveal his identity. The morning after, the body of the man is found floating in the Norrköping River. Carol decides to determine why the dead man wanted to hire her. After discovering several connections between him and the murder of Swedish Prime Minister Olof Palme, she soon finds herself in deadly danger.