"Horizon" - Travis visits his old ship while the Enterprise investigates a phenomenon-of-the-week and finds his brother in command after their father's death. Aliens attack the freighter and attach a beacon to its hull so more raiders can return later to plunder the ship. The technology can't be removed lest it explode and Travis wants to prepare the Horizon for battle but his brother objects. Travis tells his mother, the ship's medic and engineer, that he has been thinking of leaving Enterprise to return to the cargo runner. When the aliens finally make their move, Travis and Paul are able to fend them off with weapons enhancements and Paul is confident that he can captain the Horizon and convinces Travis to continue in Starfleet.

"The Breach" - A coup d'etat on the planet Xantoras means all foreign visitors have to leave the planet. Trip and Reed are sent to evacuate some remaining Denobulan geologists in planetary caverns but they don't want to leave. Meanwhile, Enterprise welcomes Antaran visitors aboard while offering assistance with their vessel and we learn that the species holds animosity towards Denobulans due to a previous war. One of the injured Antarans won't let Doctor Phlox treat him, as a result. A tribble makes a brief appearance in this ep.

"Cogenitor" - Trip takes it upon himself to educate the oppressed cogenitor, who is only used for procreative purposes as part of Vissian culture. The cogenitor decides to stay with Trip and ask for asylum, but eventually is returned to the Vissians, who later communicate the unsettling news that the cogenitor committed suicide after leaving the Enterprise. We also learn in this episode that the Vissians possess photon torpedo technology.

"Horizon" airs April 16th; "The Breach" airs April 23rd; and "Cogenitor" airs April 30th. You can reach more spoilers for each here, here, and here.