Shelley Mitchell was an employee at Lambert Smith Company.
On the day Shelley, with her boss Terry and other employee, were giving a presentation to Mr. Nagata for an advertising deal between their company and Nagata Beer; an Anomaly to the Precambrian opened in the office block and released a thick, misty sulphuric gas throughout the building. When the fog was mistaken for a fire and triggered the fire alarms, Terry atold Shelley to ignored it to continue their presentation, even as the fog seeped through the halls outside their office. Eventually, Shelley admitted to noticing a smell, so they distracted Mr. Nagata with some video mockups whilst Terry went out to investigate. To Shelley and the other man's horror, they saw Terry horribly attacked and dragged off to his death in the fog, killed by the Precambrian Worms lurking in it.
Afterwards, Shelley and the other man were left huddling in the office corner as the fog gradually began to seep into their office. Eventually, Mr. Nagata resumed the communication to tell Shelley that he'd been convinced by the presentation and congratulated her; at which Shelley comically leaned out over the table into view to thank Mr. Nagata, before using her laptop to fend off a Worm that then tried to get into the office. Moments later, the Anomaly Research Centre team arrived, using leaf blowers to keep the fog back as they escorted Shelley and the other man downstairs to safety. In the lobby, Shelley demanded to know from a speechless Nick Cutter what was going on, at which point Jenny Lewis resumed her PR duties, covering the fog up as smoke from the fire, and dismissing Shelley's talk about the creatures with the advice that she think about how the story would sound to others. (Episode 2.2)