The mystery of the locked kitchen door

We came home from work this evening to discover that our cook locked the interior kitchen door and left the key in the lock on the kitchen side, rendering the spare key useless for us to use on the non-kitchen side. And of course the exterior door to the kitchen is locked and the spare key to that door is... in the kitchen! 

We can't call our cook to come back with his exterior door key because the roads close every night and he lives so far out of town that he's on the other side of the road block. 

Thanks to Mike's security mindedness, we can't break in through either door without causing mass amounts of damage and we don't want to do that. Mike tried getting through via the crawlspace under the roof but there was no access.

We wanted a quiet night home alone tonight, but we're going to a friend's for dinner. We don't even have drinking water, because we can't drink the tap water and the distiller is, yes, in the kitchen.

This is actually the second time the cook has locked us out of our own kitchen. The first time was a Friday afternoon and we were having a party that night. Luckily he hadn't gone too far when we got home and discovered it, and he was able to come back and unlock the door.

Why would he lock the interior door? We know he keeps it closed to keep the cat out of the kitchen. That makes sense. We had the latch fixed so the cat can't open the door on her own anymore. There's never any need to lock that door.