"Wow, this place is a dump!"
"Cut the chatter, Miller. Everybody keep your eyes open, and spread out. Jones, any idea where this thing is?" Smith swept his submachine gun across the room, surveying what had once been a lobby as his team flanked out to either side.
Smith, a tall thin woman peered at the tablet in he hands, "Readings are continuing to climb. Triangulation suggests that the incursion point will be ... on the fourth floor." She raised her head and looked around, adjusting the SMG danging from her harness in a tactical sling. "I'd estimate we have five to ten minutes. When do the heavies arrive?"
Kent grunted dismissively, "Fifteen at best, so we have to hold the gate at least five I guess."
Miller's voice came over the radio, "Elevator is busted, looks like somebody cut the cables or something."
Johnson, the fourth member of the team, and easily the most taciturn, checked in next. "El-tee, the stairs are clear, aside from the reek of piss and vomit." He sounded bored.
"Hold tight Johnson, we're coming to you. Miller, sweep the back, check if there's a second stairwell." Kent nodded to Smith and the pair made for Johnson's position, their footfalls crunching on dirt and pieces of broken tile and glass.
At one point the building had been a nice small office building. Like so many others in Detroit it was now an empty shell, abandoned for years, and target for scavengers looking for copper and steel to sell at scrap yards. Kent and Johnson moved up the stairs, leaving Smith at the door until Miller reported in or joined her. The stairwell smelled worse than Johnson had described, clearly at one point this building had been occupied by squatters, and the stairs had been the toilet.
The second floor was cleared and Miller confirmed that the other stairs were inaccessible, somebody had apparent barricaded the door from the inside. The team continued to the third floor, staggered advancement, clearing the way entirely before moving upward. It took nearly all of the ten minutes to clear the first three floors of the building.
The fourth floor was not empty. In the center of a haphazard pile-up of abandoned desks a crackling semi-sphere of energy pulsed, discharging electrical bolts at random.
"Holy crap," Smith said, looking not at her tablet but the gold crucifix on a chain she wore, it was floating in mid air, pulled taut on the chain by gravity fluctuations. "This is ... really bad."
"No shit," Miller said from the back, still keeping and eye down the stairs.
"Where's this sand coming from?" Kent asked as he carefully advanced. A sudden flare of electricity stopped him short and a blast of fine particulate from the sphere suddenly pelted the group.
"That's not sand boss, its whatever is trying to come through that unstable gate!" Smith was hunkered down, tapping away at her tablet, "We need to close that ASAP, before whoever or whatever is on the other side figures out how to lock it down."
Summary - in the urban ruins of Detroit a portal to some other world begins to open, leaving a small team to either close it or deal with whatever comes through...