The trailers make “St. Vincent” look like your basic slapstick comedy movie. It was because of the trailers I wasn’t really looking forward to seeing this.

I am so glad I went.

Bill Murray plays Vincent, a grumpy, almost-mean old man who very-grudgingly agrees to babysit his next-door neighbor Maggie’s (Melissa McCarthy) son Oliver (Jaeden Lieberher).

Oliver is a timid, bullied boy who is stuck into a new Catholic school when his mother leaves his cheating father. She has to work, and takes a job as a hospital technician who has to work a lot of overtime.

You’ll get a sneaking suspicion that Vincent has some good inside right away. His rough treatment of Oliver hides some good lessons — be heard, stand up for yourself, don’t be afraid to fight. Of course, Oliver sees these things inside a ramshackle bar, at a race track and with Vincent’s extensive meetings with pregnant Russian stripper Daka (Naomi Watts).

The boy also sees the sneaking tenderness Vincent shows as he visits — and does the laundry for — a mystery woman in a nursing home. He pretends to be a doctor as he visits Sandy (Donna Mitchell), and everyone there seems to know him. When the boy does stand up for himself to his biggest bully, his world changes. As many boys do, the two former enemies become friends.

Vincent has his own problems, and after a run-in with a bookie (briefly played by Terence Howard) the older man has a stroke. Oliver finds him. Saints play an interesting role in the film. It’s a subject the boy’s teacher, Brother Geraghty (Chris O’Dowd) speaks of often.

Murray’s take on Vincent is wonderfully layered, from his acerbic commentary to his struggle to regain that ability as a stroke victim, he is at his best. For once, McCartney isn’t playing a buffoon. Her role of overwhelmed wife, mother and woman is a good change for her and shows more range than I thought she had.

The boy is delightful. His glaring honesty makes everyone take a personal inventory and everyone benefits.

I dare you to watch “St. Vincent” and not be delighted by it. The loveliness of this film will sneak up on you, while Murray’s wisecracking old man will keep you laughing, and you may just wipe away a tear or two.