Emergency, meaning a squirrel shows up inside!  In your bedroom, your basement, fireplace or living room.  First thing to remember:  DON'T PANIC!   No big deal, happens all the time. There is really only one successful procedure, and YOU can do it!  Try to close him off to one area by closing doors, etc.  If there is no door, a hanging sheet or blanket will do. Once he is closed off, go in, open all the windows and screens in that room and leave him alone for a few hours.  He'll go out on his own.   DON'T try to chase him out. He will only hide and it will take longer for him to go out on his own. Don't be afraid to enter the room he is in to open up windows - he is in a strange environment and will hide from you.  Squirrels are diurnal, and won't leave at night, so if you discover one in your basement, say, at night, just leave a basement window open that night, and he will leave first thing in the morning.  Close the window in the mid-morning, then leave a cracker, smeared with a little peanut butter, in your basement, on the floor, for a day or so, to be sure he's really out.  If your basement window has a ledge, put another cracker up there too.  If a squirrel is still in that room, he will be attracted to a window and will soon discover the cracker. Squirrels trapped in an area of no escape will also be looking for water pretty quickly. They will be in dire need of water after about three days.  They usually won't last (without water) much longer than about four days and they will find a water source if they can, using sinks, open drains, toilets or condensing pipes. IMPORTANT:  Find out how he got in.   He'll be back.