It’s not surprising that newcomers Fistful of Mercy pretty much sold out their first U.S. tour. Check the members: two-time Grammy-winner Ben Harper, veteran rock singer-songwriter Joseph Arthur and Dhani Harrison, the son of late Beatles guitarist George Harrison.

More astounding is that before the three united for an intense three-day recording session in Los Angeles, which produced their beautiful debut “As I Call You Down,” neither Harper nor Arthur knew Harrison.

The session was something of a blindish date, set up by fate and circumstance: They were all in the same place at the same time and Alexander Graham Bell’s little gadget filled in the gaps.

“Ben and I have known each other for years and talked about collaborating for a while,” says the New York-based Arthur.

His solo tour landed him in Los Angeles earlier this summer with a week of spare time. He invited Harper to guest at one of his Troubadour shows and the two got to talking about that collaboration more seriously. They booked a studio without writing a single note or knowing what they were going to do. As it quickly developed, what they first thought was going to be a little acoustic jam snowballed when Harper, who happened to frequent the same skate park as Harrison, though they knew each other only by sight, wangled an introduction.

“Ben said, ‘Do you know Dhani Harrison?’ and I said, ‘No, why is he in our band?’ Ben was like, ‘Yup.’”

Trading Dollars for Mercy

Fistful of Mercy’s name is a warm and cuddly twist on the title of a Sergio Leone spaghetti western, “A Fistful of Dollars.” “When I was talking with Ben about what we should call our band, one of the first thoughts I had was The Good, the Bad and the Ugly. But Damon Albarn has that already.”

Fistful of Mercy
Tonight, 7:30
Somerville Theatre
55 Davis Square, Somerville
MBTA: Red Line to Davis