He turned and looked toward the family room. Then moved to the doorway and peeked in.
(he's in the living room and peeks into the family room)
- Is 'in' correct? Is 'inside' a better choice?
- Is 'peeked' a good choice if he's afraid someone is in the family room and he doesn't want to be seen before entering?
No. It isn't wrong, but it isn't as good because it's unnecessary.