NEW YORK — The thing about one-person shows is, you usually have to like the actor as well as the character they're portraying.

In the case of "Every Brilliant Thing," Duncan Macmillan's affecting, memorable new play about serious depression, that's not a problem at all.

Tricky and emotional subject matter is perfectly served by Jonny Donahoe, a popular British actor-comedian who seems a naturally ingratiating and pleasing storyteller.

Donahoe is instantly likable as the unnamed narrator, in the hour-long North American premiere that opened Sunday night at the intimate downtown Barrow Street Theatre. Impish and quick-witted, Donahoe connects with the audience before the play even begins, assigning lines they will call out on his command.

The focus of the play is a list of good things that a young boy creates to cheer up his depressed mother, starting with ice cream. The list takes on a life of its own as the boy matures, and even when the tale segues into his first important adult relationship, the list remains in the background, ready to serve when needed. The effect of depression and suicide attempts on suffering relatives is at the deepest heart of the story.

Directed by George Perrin, Macmillan's sometimes heartbreaking work alternates humor with somber moments, and includes snippets of popular songs that the narrator's family sometimes sang together.

Macmillan credits Donahoe with helping co-author the play while performing it in development, and he's adept at using gentle, humorous persuasion to handle audience members who stand in for the character's relatives and friends.

The generally mirthful atmosphere can take sudden turns when something bad happens in the narration. Which it does, several times. And then we remember that it is, after all, a play about depression.

But it's also a play about trying to fight depression, and the items on the list are often very funny, like "Kind old people who aren't weird and don't smell unusual." And the play is ultimately life-affirming, as one would hope, even though it bravely faces the realization that you may not be able to make the people happy that you love.