The heroes easily make the top landing of the stairs before the large double doors slam shut and seal once more. In the main chamber the party can see and hear the rushing of water pouring from holes in the ceiling at an alarming rate, though the party is so far dry.
The stairs themselves terminate at a short landing. A rusty iron door stands to the north, but before it rests an armored skeleton, impaled on a long, iron spear. As you approach, the spear withdraws into the wall with a hiss, dropping the skeleton to the floor with a clattering from the new pile of bones.
You try the door, but it is locked! You seem to be trapped!