What happens when a gate opens in a location where there is already a monster?

Also what happens to the monster guarding the gate (and evaded) when a gate is closed and sealed, since the rules state that monsters cannot appear in sealed locations?

This situation occurred last game and we were not sure what to do: The investigator returned from an OW, ignored the monster at the gate but then failed to close and seal the gate. Next turn the investigator evaded the monster and then (since the investigator had not moved from the location and so retained the explored marker) closed and sealed the gate, leaving the monster sitting in a sealed location. Next turn the investigator evaded the monster again and made a quick escape into the streets... Same turn the mythos card caused a gate burst at the location resulting in a gate and another monster appearing... Should the original monster be shunted into the streets? Should the original monster have been shunted into the streets once the location was originally sealed?

E.

Monsters are unaffected by gates. Likewise, gates are unaffected by monsters. So nothing special happens: the gate opens, and another monster appears out of the gate to join the first monster. When the gate is closed, the monster(s) on top remain unaffected, save for those matching the gate's symbol. The elder sign also does not affect the presence or movement of monsters: it only affects "a monster appears!" Think of elder signs as sealing inter-dimensional gates, and it's through these gates that monsters normally "appear."

A house rule by Richard Launius offers that monsters on gates get removed when the gate is closed.

Tibs said:

Wasn't it mentioned in the FAQ or somewhere that sealed locations are for all intents stable? I know this wouldn't affect most monster movement but it would affect a monster appears and Hunting Horrors.

Right, I believe that's the case. There are a few interesting consequences associated with that. Those I can think of are:

• Hunting Horror
• Windy environment
• Professor Rice

What's nice about the revised Dark Pharaoh environment "Sandstorm" was that it was not changed to say "stable locations": it still says "locations marked with a green diamond." Not only does it preserve the theme of the card (sealed unstable locations don't suddenly have a "nice reputation), but it could be seen as implicit evidence that sealed locations were always considered "stable."