The silence in this adaptation “after” Anton Chekhov’s The Seagull is startling. So do the intermittent spoken words, which sound almost like an intrusion, and occasional lines of music. For the first 30 minutes, there is just signing on stage (Flemish Sign Language translated into British Sign Language), with screens translating dialogue. Damiaan De Schrijver and Van Opstal’s set design on a traverse stage exposes the construction of its effects. Then again, at its best, this play dazzles and contains a fresh, dangerous quality, as physical as a gut-punch in its climatic moments.