The Guardian is a 1984 American thriller film directed by David Greene and written by Richard Levinson and William Link.
The film stars Martin Sheen, Louis Gossett Jr., Arthur Hill, Tandy Cronyn, Simon Reynolds and Tom Harvey.
So they employ ex-military man John Mack (Louis Gossett Jr.) to protect their building as a security guard.
Mack's techniques are precise and intense, and soon his overbearing and power-mad nature begins to chafe resident Charles Hyatt (Martin Sheen).
The ending illustrates how Charles Hyatt comes to terms with the necessity of having a tough, no-nonsense security guard in order to protect the residents in their part of town (albeit reluctantly).