We are in 1917, at dawn. The pilots of SPA 150 squadron are getting ready for escorting an observation aircraft. A mechanic is launching the propeller of Lnt Decaix's Spad fighter. Sergeant Chavastelle, piloting n° 5, take a glance at "Domino", the squadron's mascot. On the left side, an unlucky pilot tells an officer that his engined has broken down.