Blu Spy runs into the RED base. There is 1 RED soldier, a RED scout and what looks like a RED spy disguised as a BLU heavy. You go for the scout first. He is standing perfectly still and holding The Sandman. He looks like he's away from keyboard. Here goes. He equipes the Knife. He runs up to the scout and goes straight into a backstab. He is dead. You immediately use your Cloak & Dagger because the enemy spy is looking around for you. You run off and disguise as a soldier. The spy is next.
The enemy spy is slowly walking outside. Nobody else is around, conveniently. You walk up to him slowly, so he doesn't see you and suspect something. You equip the ambassador. You stand still and aim. You fire twice. He is killed after the second shot in the head. You disguise as an enemy heavy. The soldier will surely suspect you because there is no heavy on his team. You try anyway.
You walk up to him quickly. He looks at you. He equipes his shovel and hits you. You feel pain and come to the conclusion that the disguise will not work. You shoot him once in the chest and he runs into you. He hits you with the shovel again, you have very low life. You run away and use your Cloak & Dagger. Conveniently there is a health pack near you. You walk into it and have enough health to kill the soldier. You run up to an area where he cannot see you. He walks in the range of your gun foolishly. You shoot your ambassador straight into his head and he falls to the floor.
You have won. You taunt and get ready for the next round.