1.Bg2 (no threat)
1...a1 any 2.Qxa1 g6 3.Qa8+ Kxf7 4.Qf3; if 2...e5 3.Bd5 and 4.Qa8; if 2...Kxf7 3.Qf1+ Kg6 4.Be4
1...e5 2.Bd5 a1 any 3.Qxa1 threat 4.Qa8; if 2...e4 3.Qxe4 etc. if 2..g6 3.Qxh6
1...g6 2.Qxh6+ Kf7 3.Qg7
1...Kxf7 2.Qf1+ Kg6 3.Be4
A Bristol-style line clearance, taking place two moves before the queen arrives on the line.