Early one morning, a fire started in a combustible trash-and-debris pile in a vacant building owned by Dorothy Gross (defendant). The fire spread across a narrow street and damaged the premises owned by Joseph Tartaglia (defendant) and used for business purposes by JACTCO, Inc. (defendant). After the fire was extinguished, the City of Philadelphia (defendant) contracted with Thorne Equipment (defendant) to demolish a burned and damaged six-story elevator shaft on Tartaglia’s property. During the demolition process, a portion of the elevator shaft fell onto and damaged property and vehicles owned by American Truck Leasing Company (American) (plaintiff). American filed suit against all of the defendants to recover damages. The trial court dismissed American’s claim against Gross and held that Gross’s negligence in allowing the trash-and-debris pile to accumulate was not a substantial factor in causing American’s loss. American’s claims against the other defendants remained intact. American appealed the trial court’s dismissal of its claim against Gross. The Pennsylvania Supreme Court granted certiorari to review.