One of Infocom's most famous games was Deadline. It was originally published in 1982 and established the Interactive Fiction (IF) could go beyond the traditional genre of Dungeons & Dragons style adventure games like Zork. Deadline was a murder mystery written by Marc Blank and it set a high standard for future IF authors who wanted to extend games into Science Fiction and other genres and styles.
Deadline was not only a breakthrough game in its establishment of a new genre, it was marketed in brilliant fashion in a unique dossier with police lab reports, fingerprints, a photo of the body, transcribed interviews and even some suspicious looking pills!
These supplemental materials helped establish Infocom's unique position as a creative force in the industry.
The game Deadline is available in several Infocom collections such as the Lost Treasures of Infocom and the Classic Text Adventure Masterpieces CD ROM collection. And you can download a version written in Inform from IFDB. However, keep in mind it's quite a difficult game. If you need the InvisiClues or maps, you can also find these online at various Infocom sites.