A session in the Shadowfell [4E]

[OMG PONIES]

I currently have a party of 6 5th-level characters that have just entered the Shadowfell (Gloomwrought, to be exact). While their primary objective should be getting home, as they did not intend to enter this plane, I want to make the plane come alive. What are some ideas for scenarios I can throw at them, interesting encounters, or possible skill challenges/sidequests?

[kieza]

Someone who recently died on the Shadowfell knew a way back to the Material Plane. If the group can catch up to his soul as it makes its way down the River of Souls, they can try to get the information out of him, but they'll have to watch out for the angels of death that try to prevent people from interfering in the passage of the deceased.

People (NPCs who they know) are looking for them near where they disappeared on the Material Plane. Thankfully, there's still a portal hidden near there...but the people searching for them have reflections in the Shadowfell, and the reflections are looking for them too...