Man at the door

It was dark. A man appeared at my door. From a distance he looked just like my brother. What the hell are you doing here? I thought.

The man wasn't my brother, but a new neighbour. The feeling of disbelief, shock, concern is proving hard to describe, but one I must pin down. A vaguely similar scene in my novel is written but I just need that clarity of expression. Testing? Damn right it is!