Wallace became active in the Liberal Party and contested Blackpool in the 1931 general election as one of a handful of Independent Liberals , who rejected the National Government , and the official Liberal support for it, and strongly supported free trade .  He also bought the Sunday News , edited it for six months, and wrote a theatre column, before it closed.  In the event, he lost the election by over 33,000 votes. He went to America, burdened by debt, in November 1931. Around the same time, he wrote the screenplay for the first sound film adaptation of The Hound of the Baskervilles (1932), produced by Gainsborough Pictures .
Lang's most seminal film was M (1931, Germ.) - his first sound feature (bridging the gap between silents and talkies). It was an expressionistic psychological thriller about a child molester serial killer. The pedophile-psychopath was identified as Hans Beckert (Peter Lorre) - his coat back was marked in chalk with the letter "M." He was caught hiding in an attic, and taken to a large abandoned brewery building to stand trial, where he was questioned by a panel of underworld boss-leaders.