Tough guy Ernie Mott...and his life-battered widowed Mom (played by the great Ethel Barrymore-great aunt to Drew Barrymore) live on the bottom edge of London society. Ernie is the kind of guy who the law might sorta watch...but he does benefit from the counsel of a few older men he calls "Dad"...Will this Diamond in the Rough Ernie Mott make wise---or foolish choices??? The other reviews above suggest potent reasons why this is the best film the usually suave Cary Grant made. This really good film brings out the better reviewers!!! Grant, in real life a Cockney, had to usually play his "Smooth Romantic Leading Man" in too many movies...NONE but the Lonely Heart-is an exception! This film also enticed the great stage actress Ethel Barrymore into 10+ more years as a wonderful character actor. Tho no longer young, she absolutely dominates any scene with her wonderful old beauty and her elegant yet streetwise wisdom. (PS I heard that she was tough...She stood up to a abusive husband!) You get the sense of LOSS as the beginning narrative hints that Ernie Mott might well join the war dead of World War 2. (Movie is set just before WW2 erupts tho it came out in 1944.)
Mott's depth is hinted at...He fights with his mom, but sticks with her when he finds she has incurable cancer. When she is tempted to make a disastrous choice, he comforts her...As he ponders a car crash, his musical ear is so fine that he can name the stuck horn tone as "e flat". This drifter, tinkerer and piano tuner...draws you in..You care what happens to him! He is willing to stand up to a gangster (George Couloris) to marry the gangster's abused ex wife...Bravery is not a problem, tho Mott does seem to get in the way of the law.
Imagine that some wise WW2 military officer would have been glad to have the tough, rough Mott in his unit!