Siren (8 p.m., Freeform) — It’s a tale as old as time. A deadly mermaid shows up in a town once known to be a mermaid haven and wreaks violence on its citizens. Two-hour series premiere.
Station 19 (9 p.m., ABC) — Jack begins his first shift as co-captain and continues to butt heads with Andy.
Atlanta (10 p.m., FX) — Tonight’s lesson: Trust is an important issue when getting a haircut from a messed-up barber.
Nobodies (10 p.m., Paramount) — In the Season 2 premiere, a joke about a sitcom based on Larry’s life becomes more than a joke when Ben and Melissa get involved.