After you can grab Edgar's key you would need to get it out of the spa.
Is there other way out?
How about the roof?
Well, you have smuggled stuff in from the roof.
Not the window. Are there any other ways into the spa, from the roof?
The vent. It is connected to the spa.
You could use some tool. Some really great and awesome tool that will change the whole future of catkind! (trademark pending)
Now, open the grate down at the spa. You can put the key on the hook.
Go back to the roof and pull the whiphook, and the key, to you.