Ghost was a TF141 soldier, good stealthy, emotionless etc all that good stuff.

Wearing a skull mask scared everyone shirtless, noone wanted to be around him

But enough of that, let's focus on the real deal here.

Abandoned building

The team were assigned to explore it, it was said to be haunted by a spirit. Noone knew who the spirit was.

They only knew it was a missing child who died because of abuse there for years.

Ghost and Soap were exploring one half while Gaz and Price explored the other.

As Soap was walking beside Ghost, they heard footsteps, but noone was around.. Was it the spirit?