The plot of Rinaldo, drawn from Tasso's Gerusalemme liberata, involves a Christian hero's exploits in the Holy Land during the First Crusade. Introducing the attractive young mezzo-soprano Natasha Hoehn to portray the armor-clad Christian general Goffredo, Pippin got a big laugh remarking that “they just don't make castratos like they used to.” A quibbler might note that Goffredo was actual a “travesty role” written for a female contralto, but the comment nonetheless was apt for the title character Rinaldo, written for the castrato Nicolini. Elspeth Franks took on the part of Rinaldo with unqualified success, singing with rich intensity and potent expression. She was equally at home in legato phrasing like that of finely wrought lament “Cara sposa,” and in virtuosos showpieces like the battle cry “Or la tromba,” a thrilling display full of bristling energy (nicely partnered by the trumpet obbligato of Matthew Brooks). Franks offered a tasty assortment of vocal shadings and convincing assurance in making the tricky transitions between the sections of the da capo arias. She mastered the challenging passagework of “È incendio fra due venti” (A flame between two winds) despite some disarray in the orchestra.

As Goffredo, Hoehn got off to a slightly shaky start in a part that may have been too low for her, seeming reticent and nervous, but with an appealing voice and sweet tone in the midrange. She seemed most at home in the cantabile-style continuo aria “Sorge nel petto,” though it called for more breath support and a better awareness of the text.

Jane Hammett, as Rinaldo's love-interest Almirena, used her agile and light soprano to winning effect in her sprightly opening aria, “Combatti da forte,” spiced with some sparkling embellishments, but with scant enunciation. In her evocatively pastoral “Augeletti,” Peter Bassinger piped the pictorial bird song on sopranino recorder. Hammett's singing of the famous “Lascia ch'io pianga” was touching if a bit flaccid and under-sung. She made nice work of the engaging hemiola — metric jostling between 2/4 and 3/8 — in the breezy “Bel piacere” — a hit Handel recycled from his big Venetian success Agrippina — made more lithesome by the absence of continuo so that the voice floats airily along with a solo violin.

The bad guys have the most fun in Baroque opera, and Lee Stawn had plenty of it as the Saracen king of Jerusalem, Argante. His rootin-tootin entrance aria “Sibilar gli angui d'Aletto” (I hear the hissing serpents) got a rousing boost from his clarion high baritone sound, full of vigor enlivened by crisp diction. He was villainously pompous in the angular “Basta che sol tu chieda,” and boisterously ebullient in “Al trionfo del nostro furore.”

The villainess Armida gets most of the great scenes in this opera. As this spiteful sorceress smitten with Rinaldo, Marcelle Dronkers used her large voice and forceful presence to raise a stirring ruckus in the vengeful “Furie terribili.” Her flirtatious “Molto voglio” — nicely enhanced by the eloquent oboe of Janet Archibald — found Dronkers a little under pitch and shrill. But she excelled in the dramatic scena “Dunque, i lacci d'un volto” with powerful delivery and a solid top, convincing in her character's vascillation between loving the ungrateful Rinaldo and wanting to kill him. In the subsequent aria “Ah, crudel,” Dronkers achieved a majestic portrayal, despite a few more moments of flawed pitch, with exemplary breath control and long spun lines. She handled the coloratura and trills with skill in the martial “Vo' far Guerra,” which calls for a rare harpsichord cadenza. Pippin's was short but effective.

Kelly Powers made her Pocket Opera Debut with suitable vocal allure as a mermaid, while a couple of other roles were eliminated without ill effect. The “Pocket Philharmonic” — led with authority and flair by George Thomson on first violin — made a jolly good sound in the sinfonias, marches, and battle pieces where delicate coordination was not as issue. But they had some trouble with the tricky cadential passages in the arias, hampered by the physical arrangement on the tiny stage, with the singers down front and out of eye contact with the players.

Rinaldo will be repeated on Sunday, April 4 at the Ralston Ballroom in Belmont.