Spike first appears arriving with Riley and his gang to Shadow, Chance and Sassy's aid when they were confronted by Ashcan and Pete. Sassy first mistakes Riley and his gang for reinforcements for Ashcan and Pete, and Chance flees. Spike then lures Pete where Sassy is standing, who drops a flower pot on Pete's head. After Ashcan and Pete fled in defeat, Riley and his gang introduce themselves to Shadow and Sassy and ask them who was the other dog that fled. Shadow says it was Chance, so Riley sends Delilah to find him. While looking for them, they notice the blood-red van, driven by Jack and Ralph coming and hide, while Spike hides under the car with Riley, Shadow and Sassy. After Jack and Ralph are gone, Shadow asks Riley where the Golden Gate Bridge is. Riley replies that he knows where it is, but he refuses to help Shadow and Sassy due to there being too many humans.
Spike was later seen witnessing Shadow and Sassy rescuing a boy named Tucker and his pet cat Tiger from the family's house that had been set on fire by a careless Jack and Ralph. Riley was impressed at them for saving Tucker and his pet cat and decides to help them. When they return to their home at the warehouse by the docks, they find Delilah and Chance already there resting. Bando gets into a fight with Chance, but Riley intervenes. Spike then comments that Chance and Delilah were probably kissing and stuff, much to his disgust.
Sometime later, Spike was inside with Riley and Shadow, while the others are outside watching Chance playing with a trash bag. However, Jack and Ralph in the blood red-van suddenly arrive, and they all rush back inside except for Chance, who is still busy eating out of the trash bag. Chance gets captured by Jack and Ralph and puts them in the blood-red van. Riley and his gang finally rush out to Chance's aid, but they are too late due to them being in the highest floor where they hide as the blood-red van drives away, but Riley decides to outrun them. After blocking them, Riley and Sledge deals Jack and Ralph while Sassy frees Chance and the other captive dogs, who then chase Jack and Ralph away. Bando then sets the blood-red van in reverse and it falls into the river.
Spike was last seen watching Riley return back after he leads Shadow and Sassy (Chance left earlier after Delilah reluctantly dumped him) to the Golden Gate Bridge, and he presumably allowed Delilah to leave his gang to be with Chance. Spike was not seen afterwards, as he likely went back to Riley and his gang and still remains there.
- Though he is a puppy and the youngest member of Riley's Gang, Spike acts sensibly like his fellow members and is less immature than Chance.