ST. PETERSBURG — Right from the beginning, John & Jen gets its principal point across, as 6-year-old Jen sings Welcome to the World to her newborn brother, John."The people you love the most are also the ones who make you cry," she croons, leaning into his crib. "I'm not sure why."The bond between siblings is at the heart of John & Jen, now playing at Freefall Theatre, and through that prism, this intimate, two-actor musical by Andrew Lippa (music, book) and Tom Greenwald (lyrics, book) is an emotionally riveting portrait of American family life during a time of wrenching change.Katie Zaffrann plays Jen, while Chris Crawford plays two characters named John: Jen's brother in Act 1 and her son in Act 2. Though both of these excellent actors are equally engaged in the story, Zaffrann's Jen is more completely developed. She goes from self-possessed big sister to '60s flower child to single mother in her 40s, while Crawford's two Johns remain forever young.During childhood, Jen tries to protect John from their abusive father, but when she goes away to college, her kid brother feels abandoned. To please his father, he eventually enlists in the Navy and is killed in Vietnam. The first part of the musical has some peppy numbers, such as John's hilarious razzing at his sister's high school basketball game in Dear God, but the dramatic arc is inexorably downbeat. In their final scene together, when Jen announces to John (now "one of those John Wayne army men") that she is moving to Canada so her boyfriend can dodge the draft, the bitterness between them is devastating. "You're not my family anymore," John sings in Run and Hide.Zaffrann gives a rich, multifaceted performance, ranging from cowbell-clanging baseball mom cheering for her embarrassed son at a Little League game to sad-eyed sister on a visit to her brother's grave and marking in Just Like You the passage of time: "You're completely in the shade now. It's amazing the way this tree grew."Crawford's portrayal of brother and son is exuberantly physical (Bye Room on going off to camp is a hoot), laced with boyish resentment and dependence on his big sister, then his mother.Eric Davis directed (he was also responsible for costume design) with a sure hand for the actors, drawing superb work from them, and impeccable taste in his staging, which is done runway style, with the long, relatively narrow performance space flanked by banks of seats facing each other. At both ends are stacks of TV screens on which relevant images play, such as family snapshots, footage from the Vietnam War and photos from the Summer of Love.The scenic design (by Jerid Fox) and props (Allison Davis and Chloe Davis) are smartly detailed — including John's Louisville Slugger, period newspaper front pages embedded into the stage floor and a Star Wars pillow case — to create a sense of full immersion in the family's experience. Music director Chris Brent Davis leads an offstage band of piano, cello and percussion in the inventive orchestrations by Jason Robert Brown.It goes without saying that John & Jen speaks to sisters and brothers, mothers and sons. For baby boomers it will hit close to home, and for anyone who loves musical theater somewhat off the beaten track, it is a journey well worth taking.John Fleming can be reached at [email protected] or (727) 893-8716.