Della Galway has just started a new job and and is quite pleased with her new flat. It's is a quiet, low-crime neighborhood and the landlady is as security conscious as she is. The only problem is the the rent is a bit high so she advertises for a roommate at work. Rosamund has just split up with her live-in boyfriend and decides to move in with Della. The two couldn't be more different however with free spirit Rosamund unable to understand Della's near fanaticism about locking doors and windows. It all comes to a head when Rosamund brings her new boyfriend home late one night.