NBC is airing an unusual hat-trick series crossover.
The three-parter begins at 10 p.m. EST Tuesday on "Chicago Fire" and wraps up Wednesday on the two other NBC dramas airing back to back from 9-11 p.m. EST.
Making the ambitious crossover feasible: All the shows are produced by Wolf Films in association with Universal Television.
Producer Dick Wolf said linking the two Chicago-based shows made sense, while drawing in New York-based "Law & Order: SVU" was a "little tricky."
"But it wasn't too far-fetched to develop a story about child pornography that crosses state lines," Wolf said, which he called a sad reflection of reality.