ENT Season 2 Episode 20 Horizon

At the direction of Starfleet, Enterprise makes a detour to a planet passing between two gas giants in order to observe the gravitational forces and subsequent volcanic activity. Their new course takes the ship close to that of E.C.S. Horizon, the cargo vessel where Ensign Mayweather grew up. He requests permission for a further detour to rejoin his family on Horizon, as his father is ill and he hasn't been able to visit him in four years. Captain Archer readily agrees, but bad news arrives when Mayweather learns that his father died some six weeks earlier.
As planned, Mayweather boards Horizon and receives a warm welcome from most of the crew, including his mother Rianna. He finds that his brother, Paul, has been named acting captain, but he doesn't seem to be coping well with his new responsibilities. Mayweather offers to make a few repairs and upgrades to systems on the ship, but Paul tells him to stop, making him feel uneasy and out of place. Soon afterward the ship comes under attack, and a homing device is placed on the hull. Mayweather then recommends a boost in the ship's fighting capability, but Paul insists that the safest course is to flee to the nearest port and yield the cargo as needed.
Back on Enterprise, Commander Tucker arranges a movie night for the crew featuring the Frankenstein film trilogy, and invites Sub-Commander T'Pol. She eventually consents, and finally finds in the film an insightful view into historical human-Vulcan relations. Meanwhile, Mayweather makes his intended modifications without permission, resulting in a confrontation when Paul finds out. The ship comes under further attack from an alien vessel, and Paul offers up the cargo as planned. The aliens refuse and demand the vessel as well. Left without any other option, Paul tells Mayweather to reinitiate the modifications and to detach the command module from the cargo section. They soon disable the alien ship. The brothers reconcile and Mayweather leaves, promising to visit again soon.