One is a number that can represent many things: a marriage joining two people together, a shared tradition, a blending of two unique talents.

For renowned Celtic fiddlers Natalie MacMaster and Donnell Leahy, its all of the above. One is also, appropriately, the title of their CD, the first the couple has recorded together.

The duo will feature music from the CD when they perform their Visions from Cape Breton and Beyond: A Celtic Celebration concert Monday night at Monomoy High School in Harwich. The concert is presented by the Harwich Cranberry Arts & Music Festival.

Who: Natalie MacMaster and Donnell Leahy

What: Visions from Cape Breton and Beyond: A Celtic Celebration concert

When: 7 p.m. Monday

Where: Monomoy Regional High School theater, 75 Oak St., Harwich

Tickets: $30, $40, $60 and $90; available at Brown Paper Tickets at natalie.brownpapertickets.com or 800-838-3006

For wheelchair-accessible seating: 508-432-1885 or cranfestproduction@hotmail.com.