Most classical ensembles that want to expand their horizons explore contemporary music, but a cappella choir The Esoterics already lives there, performing no music more than 100 years old (much of it less than 10). So to try something new, they have to reach far back. This weekend the choir will perform Carlo Gesualdo's Tenebrae responsoria on, as it happens, the work's 400th anniversary. The Tenebrae service is held on Maundy Thursday (the day of the Last Supper), Good Friday, and Holy Saturday, and The Esos will perform this choral cycle (long enough to require three evenings, with about 50 minutes of music for each) traditionally, by gradually extinguished candlelight. Gesualdo (1566–1613) was an Italian prince and composer whose life reads something like a Dario Argento script for The Sopranos; aside from stabbing his wife/cousin and her lover, he's best remembered for his intoxicatingly shifty and lurid harmonic language, nothing like it heard again from composers until the late-romantic period. "The thing that's really fascinating about Gesualdo to me," says director Eric Banks, "is that he was writing chromaticism that keyboards were unable to play at the time [not yet being equipped with the complete range of white and black notes], and God knows if singers were actually able to do it." As a bonus on Thursday, Banks' other choir, the Cornish Chamber Singers, will perform composer Paul Crabtree's own contemporary Tenebrae settings, some of which borrow from Bob Dylan songs ("Positively 4th Street," "The Wicked Messenger," and seven others). Borrow how? Banks says "characteristic chord progressions" and "a few harmonic and/or rhythmic quotes." One ticket ($10–$20) gets you in all three nights, so keep your stub.