She nods.  "That stairwell-- can still smell their sweat... I heard the metal door bang open from back there..." she shrugs toward the direction they came from.  "And thanks..."  She heads for the fire-door to the stairwell, right in the middle of the roof, and stands to the side of it, in case there's a trap.  She tests the knob... "It's locked," she says, looking expectantly toward Titus.