According to the Merriam-Webster Dictionary the definition of “cycle” is a permutation of a set of ordered elements in which each element takes the place of the next and the last becomes the first. Using that definition, it seems safe to interpret the new musical production “Los Otros,” now playing at A.R.T., a song cycle. Two characters, Lillian (an enthralling Luba Mason) and Carlos (an embolden Caesar Samayoa) each take their turn, repeatedly, describing eventful moments from their past that will eventually shape the future. The book and lyrics by Ellen Fitzhugh embrace each memorable event with precision and clarity that captures the emotions of each character and the mood and tone of the occasion. Michael John LaChiusa, as always, provides music that pinpoints every turn of emotion, sometimes evoking a thoughtful whisper or at times seeking to revel in joy while it connects and supports the lyrics with a variety of rhythms.

We meet Lillian as a child living in government housing near San Diego where she has her first encounter with illegal Mexican immigrants as they jump from a train and camp in cave as the first part of their journey to escape to America. Sneaking out at night with her friends to leave food outside the cave for the mother father and baby. As she goes through her life each memory involves interaction with different Mexican immigrants. Traveling to Tijuana to find and smuggle a housekeeper across the border. Seducing a Mexican teenage virgin when on a drunken binge. Meeting the housekeeper’s family when she returns years later, after leaving to return to Mexico.

We alternately meet Carlos as he leaves Mexico to find a new life as a gay young man in America. We share his time as a salesclerk after school in Carlsbad California, when he was twelve and then his experiences when he was a migrant worker picking plums in Santa Rosa during the summer. We learn he has become an IBM accountant and has become the vengeful long-term partner of a white man who was once the escort for Ava Gardner.

Mr. Samayoa gives a sensitive and endearing performance capturing the monumental moments experienced during the journey of a gay Mexican man immigrating to America. His vocals are strong, clear, and emotional. Ms. Mason creates a complex Lillian who struggles with her feelings and decisions as she maneuvers her way through a maze of unfortunate circumstances. Even though the choices are puzzling she secures them firmly in reality. Here vocals are pure, evocative, and seamlessly intertwine with the narrative. It is a joy to watch both incredible actors give tour de force performances.

Finally, their two lives intersect as we discover what each has in common with the other. The story is complex in its simplicity and gratifying in its humanity. The structure is narrative, so the development of secondary characters who never appear sometimes suffers but does not diminish the strength of the story. The set design by Junghyun Georgie Lee is sparce but effective and the costumes by Alejo Vietti are appropriate. The sound design by Ken Travis is so efficient, clear, and natural that he makes it difficult to even notice the performers are amplified. It is a small chamber musical that is human, compassionate, and genuine with performances that should not be missed.