Did someone murder Shay? That was the question on everyone's mind at the end of last week's episode of Chicago Fire when the team discovered a storage unit filled with suspicious materials and a newspaper clipping about her tragic death.

In this exclusive sneak peek from Tuesday's new episode (10/9c, NBC), Severide (Taylor Kinney) and Dawson (Monica Raymund) call in Atwater (LaRoyce Hawkins) from Chicago P.D.'s intelligence unit to do a little digging. "These are accelerants every arsonist knows about. At least the slick ones," Severide tells Atwater in the unit.

On the set: Go behind the scenes of Chicago Fire

So what is Atwater's next move? Watch the exclusive video to find out:

Chicago Fire airs Tuesdays at 10/9c on NBC.