Maryland rapper Q Da Fool has plenty of stories to tell. (Evan Pierce)

When Q Da Fool raps about the brutality of contemporary street life, he usually sounds like he’s having the time of his life. How does that work? “I was probably just in a good mood that day,” says the 21-year-old. “Whatever mood I’m in that day, that’s how I rap.”

Truth be told, he’s been in a pretty good mood all year. After signing a record deal with Roc Nation in May, the Largo native has been working closely with Zaytoven, the astonishingly prolific trap producer who helped launch Migos, Gucci Mane and Future into rap’s highest stratospheres. Q is hoping to follow a similar trajectory later this summer when he drops “100 Keys,” a mix tape produced by Zaytoven, front to back.

He has plenty of stories to tell, too. Over the past six years, Q has been in and out of rehab centers and correctional facilities — places where “I could get my mind together,” he says.

And during those stints, he seems to have learned rap music’s most elusive truth: that the lyrics and the emotion of a song don’t necessarily have to flow in parallel. Listen to the twinkle-and-snap of his new Zay-produced single, “The Plug,” and you’ll hear Q mood-swing his way through the hook, going from boastful, to exasperated, to incredulous, and back around again. If it sounds like he’s scowling and smiling at the same time, he might be.

Show: July 7 at 8 p.m. at the Fillmore. $35.