After the intro you stand on the patio of the mansion, with Thomas Rogers, the butler standing behind you. Go forward and follow the path until you reach the pier. Take a look at the scuttled boat and then make your way back to the mansion. On your way back you can take a side path to your left and meet Mr. Marston. After talking to him head back to the patio. Talking with Mr. Rogers and he will let you into the house.
After Mr. Rogers leaves you follow him to the kitchen. You'll see a cutscene where Ethel Rogers complains about the situation and leaves then. Take a closer look at the fruit-press and then exit the kitchen. On the back hall take the door to the right to enter the Rogers' room.
Go to the other end of the room where you see a table. On the table you can find a packet with needles and a delay letter. On the left is the Rogers' invitation letter. Copy the contents of both letters to your journal.
Exit the room and go up the stairs. Go to the linen closet, where you can see Mrs. Rogers. talk to her and offer her to give her a hand. After the small conversation leave her alone and go to the main stairs. Now you can enter some of the guest rooms.
Go to your left and take the first door right. On the right side of the bed is Armstrong's invitation letter. Take it and copy the content. Exit the room and head for the next room.
In Blore's room you also can find his invitation letter. Beside the bed you can see a diary. when you try to pick it up, Blore comes into the room and interrupts you. After the conversation you have to leave the room.
You can't enter Lombard's room yet, but you can peak through the keyhole and then knock on the door to have a short conversation.
Knock on the door to talk to Vera.
Knock on the door to talk to Emily.
Peak through the keyhole and then knock on the door to talk with Mackenzie.
After you explored the second floor go downstairs to the game room.