Shadowrun Missions are a series of Shadowrun adventures published as PDFs only through DriveThruRPG and similar venues.
There have so far been six major story arcs in the Shadowrun Missions:
Seattle Story Arc 1: SRM00-01 to SRM00-05 for Shadowrun (3rd Edition).
Rose Croix Story Arc: SRM01-01 to SRM01-09 for Shadowrun (3rd Edition).
Denver Story Arc: SRM02-01 to SRM02-25 for Shadowrun (4th & Twentieth Anniversary Editions).
New York Story Arc: SRM03-00 to SRM03-12 for Shadowrun (4th & Twentieth Anniversary Editions).
Seattle Story Arc 2: SRM04-00 to SRM04-12 for Shadowrun (4th & Twentieth Anniversary Editions).
Shadowrun Missions: Chicago Campaign: SRM05-01 and onwards for Shadowrun (5th Edition).
There has also been a number of sub-story arcs:
Griffin Biotechnology: SRM00-03, SRM01-04 & SRM01-08
Rise of the Vory: Some of the SRM02 missions
The Dragon Stone: SRM02-08, SRM02-24 & SRM02-25
Trouble with the Triad: Some of the SRM02 missions
The Decline and Fall of Xeverus Cosmetics: SRM02-14, SRM02-21 & SRM02-23
4 sub-story archs in New York: Some of the SRM03 missions
Buried Underground: SRM04-01, SRM04-03, SRM04-05, SRM04-07, SRM04-09 & SRM04-11
Artifact Rush: SRM04-02, SRM04-04, SRM04-06, SRM04-08, SRM04-10 & SRM04-12
Emerging from the Wasteland: SRM05-01 to SRM05-06
From the publisher's site:
Shadowrun Missions is an international shared campaign. The goal is to have characters and adventures that all share the same universe, and of course have fun while doing it. Missions are played at local game stores, conventions, game days, and as home games. Players who participate in these scenarios will have a real opportunity to influence the Shadowrun game world, and play their characters in events worldwide.