Voight and Antonio enlist the help of agents at the Special Victims Unit in New York, Fin and Rollins, to help track down the culprit of a series of rape/murders. Burgess has an opportunity to prove herself to Intelligence. Elsewhere Lindsay enlists the help of Halstead to act as her date for her high school reunion to get back at an old rival.
The crossover starts on Law & Order: Special Victims Unit S15E15 Comic Perversion (I).
I’m watching Chicago P.D. 1×06 “Conventions (II)” https://trakt.tv/shows/chicago-p-d/seasons/1/episodes/6