A spy probe has been smuggled onboard the Firefly by an FBI agent before takeoff on a trip to Mars. The probe is trying to get evidence of the Firefly's illegal Super Firefly Drive. The Firefly is now in orbit around Mars, and the probe is free-floating in the cargo bay and taking pictures.
---
The PSA addon is a great way to explore the inside/outside of big ships such as the Firefly and others. This addon (as well as the Firefly Jumbo) is required for this scenario to work.