The Duel at Maggie Lang's House was an open confrontation between Scott Lang and Darren Cross that took place following the infiltration into Pym Technologies Headquarters.
Trying to escape by helicopter with the Yellowjacket Suit, Darren Cross and HYDRA agents were chased by Scott Lang and ants controlled by him. During the chase, Ant-thony was killed by Cross.
Lang managed to reach the helicopter, but Cross tried to kill him with a pistol, killing some HYDRA agents in the process. Cross asked Lang if he thought he could stop the future with a heist. Lang answered that it was never just a heist as Pym Technologies exploded and collapsed into the Quantum Realm.
Angered at the destruction, Cross put on the Yellowjacket Suit and started a fight with Lang. The pilots were killed in the midst of the fight and the damaged helicopter started to fall. During the fight, Lang and Cross fell into Cross's briefcase and got locked inside it before it fell from the helicopter, landing in the swimming pool of a neighboring home.
Cross returned to normal size and escaped from the briefcase. He threatened the resident family until Lang, also returned to normal size, stopped him.
They continued their fight and Lang managed to swat Cross into a bug zapper. However, Jim Paxton and Gale appeared and subdued Lang, proceeding to arrest him.