The Hi-Liners Musical Theatre in Burien, WA: Putting People Downstage Center Since 1966! Our productions, classes, workshops and camps are open to students ages 3 to 22. We are a non-profit youth theatre dedicated to providing professional direction to our young cast members to develop their talents with the backdrop of quality sets, costumes and a live orchestra, to give both the performers and the audience a genuine Broadway musical experience.