Chillin' next door

I went to return the crowbar I had leant from Crazy Neighbour™ and found Mouser chilling on one of their garden chairs on the patio, just outside their kitchen.
The neighbours are
catsitting for their son who's on holiday. So two cats are in the house. A fat blue point called Sylvester and a skinny rusty long haired female called Missy.
Mouser knows they are there and is keeping an eye on them, looking in, stalking.