Following on the heels of Mystery Case Files: Huntsville, the player is tasked with investigating the disappearance of the Queen’s Hope Diamond in Capital City. The 800 carats (160 g) diamond was stolen from the Capital City Plaza Gallery where it was on display as part of the annual mineral convention, Sparkle Daze. Prime Suspects adds items that players have to discover to unlock later levels (such as finding a battery to power a flashlight). Characters also became a more prominent part of the series with the investigation revolving around a list of 20 characters with different personality ‘quirks’.