The code below assumes that your door is called "mansion_1" (without the quotes), and your monster is called "servant_brute_1" (without the quotes).
//The Waking Up Feature that starts as soon as map loads.
void wakeUp () {
    FadeOut(0);     // Instantly fades the screen out. (Good for starting the game)
    FadeIn(20);      // Amount of seconds the fade in takes
    FadeImageTrailTo(2, 2);
    FadeSepiaColorTo(100, 4);
    SetPlayerActive(false);    
    FadePlayerRollTo(50, 220, 220);                 // "Tilts" the players head
    FadeRadialBlurTo(0.15, 2);
    SetPlayerCrouching(true);              // Simulates being on the ground
    AddTimer("trig1", 11.0f, "beginStory");            // Change '11.0f' to however long you want the 'unconciousness' to last
}
void beginStory(string &in asTimer){
    ChangePlayerStateToNormal();
    SetPlayerActive(true);
    FadePlayerRollTo(0, 33, 33);        // Change all settings to defaults
    FadeRadialBlurTo(0.0, 1);
    FadeSepiaColorTo(0, 4);
    SetPlayerCrouching(false);
    FadeImageTrailTo(0,1);
}
////////////////////////////
// Run first time starting map
void OnStart()
{   
    //Allows you to wake up
    wakeUp();
    //Add the Lantern and 10 Tinderboxes when in Debug mode, always good to have light!
    if(ScriptDebugOn())
    {
        GiveItemFromFile("lantern", "lantern.ent");
        for(int i=0;i<10;i++) GiveItemFromFile("tinderbox_"+i, "tinderbox.ent");
    }
    
    SetEntityPlayerInteractCallback("mansion_1", "InteractedWithDoor", true);
}
void InteractedWithDoor(string &in entity)
{
    PlaySoundAtEntity("", "insanity_monster_roar02.ogg", "mansion_1", 0, false);
    SetEntityActive("servant_brute_1", true); //Spawn monster
    GiveSanityDamage(15.0f, true);
}
////////////////////////////
// Run when entering map
void OnEnter()
{
}
////////////////////////////
// Run when leaving map
void OnLeave()
{
}