The Medium clock puzzle is one of the first proper puzzles you face in the Niwa Resort. Inside Thomas Rekowicz's office you'll find a clock that can change the spirit world in The Medium when you move its hands. Using that, you'll need to manipulate time in the ghostly realm to reach a secret back room. Here's how to solve The Medium clock puzzle.
How to solve The Medium clock puzzle
There are few things you can look at and examine in the office - the phone that called you at the start of the game, plans that reveal that Thomas Rekowicz designed the Niwa resort, some notes, and a torch that will stay with you for the rest of the story. However, the things you really need to pay attention to are the bookshelf in the corner and the big grandfather clock. If you activate your Insight you should see the clock highlighted in the real world, while the bookshelf will have some sort of wiring behind it that appears.
You'll know the clock is relevant because Marianne will say "I could instantly tell there was more to that clock that met the eye" when you interact with it. This is a subtle indicator that the giant glowing clock is important. The bookshelf on the other hand doesn't really do too much just yet. There are some pictures to look at, and a secret button that Insight will reveal, but until you solve The Medium Clock puzzle, the bookshelf is a dead end.
How to find The Medium clock key and start the puzzle
If you've picked up the torch in the real world, in the broken drawer on the floor by the desk, you'll probably have noticed the key underneath it. If you haven't then do that now - grab the key and use it to open the face of the clock.
Once the clock is open you'll be able to turn the hands on the face in the real work and scan through a timeline in the spirit world. This is the key to solving the The Medium clock puzzle.
To get to the next part you'll want to move the hands until you see a passage open up in the spirit world office, to the secret back room behind the bookshelf. It happens at 7:00 and 5:05, either of those will open up the way through, which you can then reach via astral projection in the spirit realm. Once the way is open, head through.
The main thing you'll want to focus on in the secret back room to solve The Medium clock puzzle is the fuse box on the back wall. Helpfully, while the game made it very clear 'hey, this clock is important' earlier, there's no reaction to the fuse box at all. Which somewhat downplays its integral part in the entire puzzle solution. Ignore the giant orange swirl on the floor too - you'd think it might be important but it isn't.
For now you can't do anything with the fuse box so leave the room and go back to the clock in the real world. If you wind the hands to 4:00 you'll find a spirit well appears on the desk. Absorb the energy and then return to the clock in the real world and wind the hands to one of the times where the passage is open: 7:00 or 5:05.
Head back inside once you've opened the way and fire a spirit blast at the fuse box. Doing so will cause a spark to travel along the wall and bring the lights back on in the real world.
Once you've got the power back on with the ghost juice you sucked out of the spirit world, head back into the office and return your attention to the bookcase. If you haven't already, use your insight on it to find a switch hidden behind one of the pictures. Move the frame and press the button to get access to the secret room for real and, when you get inside, you'll leave the spirit world and be able to press on with the next puzzle.