Task: Question Answering
Input (English): In the year 2015, spaceship IC-1 (Interstellar Colony #1) travels toward a planet similar to Earth to explore the possibility that the population problem on Earth can eventually be solved there. IC-1 's crew consists of Capt. Mead Ralston (Bill Williams), his wife Jan (Norma West), Drs. Steven (John Cairney) and Helen Thomas (Linda Marlowe), two other married couples, and four people in suspended animation. One year into the voyage, Helen is found to have a fatal pancreatic infection that can only be cured if the ship returns to Earth, but Captain Ralston refuses to turn back; and when he denies her permission to have another child, she commits suicide.[2]Steven and some of the other crew members mutiny and imprison Captain Ralston. When Capt. Ralston escapes, he forces the crew to obey him by threatening to destroy the ship. Ralston plans to execute Steven. Ignoring the warnings of the crew, he releases one of the "animates" by raising the temperature of the compartment in which it is suspended, and the "animate" kills him before dying of complications caused by the thawing out process. The ship goes on under Steven's leadership.[3], Question: Who imprisons Captain Ralston ?
Output (English): Answer: Steven and other crew members imprison Captain Ralston.