The rigors of life as a touring musician can have strange and perhaps unexpected benefits — as when old friends Celia Woodsmith (vocalist for the Grammy-nominated bluegrass band Della Mae) and Chris Hersch (guitarist of alt-country heroes Girls, Guns & Glory) suddenly found themselves with some free time.

Rather than sleep or hit an all-inclusive Caribbean resort, they teamed up to form the delicious blues experiment called Say Darling — an outfit that gleefully reimagines archival roadhouse boogie and swing through the modern prism of the Radiators and Bonnie Raitt.

See Say Darling when they headline the Blue Monday concert series in Mystic River Park. And don't be late: the excellent Sondra Levine opens the festivities.

Say Darling and Sondra Levine, Blue Monday Concert Series, 6-8 p.m. Monday, Mystic River Park, 28 Cottrell St., Mystic; free, canned goods and/or donations benefitting Stonington Education Fund and Pawcatuck Neighborhood Center Food Bank accepted; see Facebook Blue Monday.