Kevin calls the police, telling them he's being robbed (though he gives them the neighbor's address, since he plans to run over to that house, leading the burglars after him).
Marv almost catches Kevin, as Kevin runs up the attic—he grabs onto Kevin's pant leg. But Kevin spots Buzz's tarantula and puts it on Marv's face, making him scream. The tarantula crawls onto Harry, and Marv smashes him with a crowbar, trying to kill it (unsuccessfully).
(Told you the tarantula would be back.)
Kevin zip-lines from the attic to his tree house. Idiotically, Harry and Marv try to climb along the line to reach him. Kevin uses hedge-clippers to cut the line, sending Harry and Marv slamming into the wall of the house.
Kevin rushes over the neighbor's house, which turns out to have been flooded by Harry and Marv when they robbed it. Kevin makes his way through the neighbors' wet basement, but the burglars, wising up, intercept him at the stop of the stairs.
They prepare to torture Kevin in all the ways he injured them. But, first, Harry says, he's going to bite Kevin's fingers off.
Fortunately, Old Man Marley sneaks up on the burglars from behind and smashes them with his snow shovel.
He rescues Kevin and sends him home.
The cops arrive and arrest Marv and Harry, noting that they know every house Harry and Marv hit since the burglars flooded them all.
From the back of the cop car, Harry looks angrily at Kevin, who smiles and waves from his house's window.