A teacher of the deaf experiments with transmitting sound, invents the telephone, and marries one of his deaf students.
At Boston in 1873 Alexander Graham Bell (Don Ameche) asks for copper wire and hopes to teach the deaf to talk. He explains sound. Thomas Sanders (Gene Lockhart) brings Gardner Hubbard (Charles Coburn) to Bell, who is teaching Sanders' deaf son George (Bobby Watson). Bell shows Hubbard his telegraph and meets his daughters. Mabel Hubbard (Loretta Young) is deaf but reads lips and wants to marry Bell, who wants a wife. Mabel encourages Bell to work on his telegraph and on his sound invention secretly. Thomas Watson (Henry Fonda) helps Bell move his equipment. Bell tells Sanders he will still help George in Salem. Bell experiments with Watson's help, and they send sound through a wire in June, 1875. Bell happily tells Mabel they can marry. He tells her and her father of his telephone, but Hubbard does not approve. Watson and Bell are hungry and tired. Bell quits and tells Watson to go back to his job. Bell writes to Mabel, who says she will not marry him if he gives up his telephone. Bell tells Watson they must study the ear to make a receiver. Bell and Watson move again to save money. Bell faints from hunger, and Watson takes a chicken. Sanders takes them home for Christmas Eve, and Bell finds Mabel there. Bell has George say "father" to Sanders.
On March 10, 1876 Bell spills acid and calls Watson through the wire. Watson hears it, and they cheer. In Salem Bell shows an audience that Watson can speak to them from Boston, and they hear music too. Hubbard still resists the idea, but Sanders and he help Bell start the New England Telephone Company. Hubbard complains about money, but Bell and Mabel plan to go to England. Bell shows Queen Victoria (Beryl Mercer) how it works, and she orders telephones for the palace. Mabel reads a letter from Hubbard that Western Union says they have a better telephone. Sanders tells Hubbard, Bell, and Watson that they can get no more credit. Bell says they must sue for patent infringement.
In the trial Bell is questioned by Barrows (Russell Hicks). Pregnant Mabel arrives with the letter from June 1875. Bell objects because it is private; but she testifies, and the paper has the evidence. The judge (Harry Davenport) lets Bell speak, and he says that the issue is if a starving scientist is to be called a liar and thief when he benefits the world. Bell uses a telephone to call an ambulance. Mabel has a baby girl. The Western Union president (Jonathan Hale) admits that Bell invented the telephone and offers him a partnership. Bell agrees and tells Mabel that a man could fly.
This true story is substantially accurate and portrays
the struggles of a young inventor with genius and vision. He is
assisted financially by two fathers of his students and encouraged
by his wife, bringing about one of the most useful and lucrative
inventions to civilization.