We have a 2yr old neutered male cat, fully house trained and generally lovely and snuggly. We've recently moved into an upstairs flat in an old house - so he has to go out of the catflap in our door and then cross the communal hallway to get downstairs to the catflap that goes outside.
But, there's a bossy female cat in one of the other flats and they are fighting over the hall [sigh] She does lots of sitting outside our door, giving poor old Tiger the evil eye if he tries to go past her and hissing at him.
Last night, I heard our cat mewing, so got up and put him outside our front door (there's a catflap in it but he isn't that keen on them yet). Went back to bed, and when I woke up he was asleep by my door. And there was a turd on my bedside rug, and my bed itself had been pissed on while I was in it 
So... I guess the other cat didn't let him go past past night. He is being put out at night for the next few nights and the catflap locked but that's not a long term solution. Am thinking of Feliway but where to plug it in? Would the hallway be the best place, as that's where they are battling and sitting staring each other out? Would a litter tray inside be a good idea or would it confuse him?
TIA 