Saving Sir. Beefton

The Paladin of my party has a pet cow named Sir. Beefton. The paladin is convinced Sir. Beefton is a horse but that’s not the point. On the trip to the amber temple the roc grabbed Beefton and flew off with him. The rest of the party went into the temple but the paladin decided to try to climb the mountain to go and save his precious “horse.” The player was absent last session but now they’re coming back. What should I do to not spend an hour on one player’s solo mission? Not to mention the fact that they could be climbing for days.

I was thinking the roc flies down and it throws Beefton like a projectile, if they last a few rounds it flies away. I want them to be able to save their pet but I’m not quite sure how to run it.