Station 19, 8 PM on Ch. 22 and Ch. 9:

This action drama returns from an agonizingly long hiatus

(at least for its fans) with “Train in Vain,” a crossover event with sister show “Grey’s Anatomy.” As the action resumes, Drs. Carina and DeLuca (Stefania Spampinato, Giacomo Gianniotti) are on the trail of Opal (guest star Stephanie Kurtzuba), who is suspected of sex trafficking. Elsewhere, Maya (Danielle Savre) leaves Andy (Jaina Lee Ortiz) in charge of the yearly inspection, while Vic and Dean (Barrett Doss, Okieriete Onaodowan) struggle to cope with the fallout from Dean’s arrest. Boris Kodjoe also stars.

Ben (Omar Miller) is nervous about undergoing a colonoscopy, so in a show of solidarity, Wade and Forrest (Walton Goggins, Rob Corddry) schedule appointments for the same procedure at the same time in the new episode “Out With the Old.” Meanwhile, Michelle (Maya Lynne Robinson) is determined not to get involved in her sister Meg’s (Nicole Byer in her recurring guest role) boyfriend drama, but Delia (Michaela Watkins) inadvertently gets sucked into the mess herself.

In a new episode called “Get Right With God,” Clarice (Rebecca Breeds) may be very good at her job, but that doesn’t protect her from getting drugged and confined to a hospital bed by a serial killer who is part of the medical profession. Drifting in and out of consciousness, she is assailed by a vivid series of hallucinations. Michael Cudlitz, Kal Penn and Nick Sandow also star; the guest cast features Edie Inksetter and Natalie Brown.