The midnight man (1919)

Bob Gilmore, a young clubman, is called by telephone to his home, where his parents are giving him a birthday party. He overhears one of the men guests make a slurring remark about his mother's appearance, and proceeds to punish him then and there, throwing the entire gathering into an uproar. Later in the evening he assumes guilt for a check which had been in reality forged by his foster father, in order to save the mother's feelings, but obtains a written confession from the guilty man for future use if necessary. Learning that he had been adopted from a foundling asylum in infancy, Bob decides to go to New York to see if he cannot learn his real name, which he understands begins with "Mor."