Forgot the frogs...

Loved this chapter and story. Harry certainly is growing up and maturing quickly.Cool that he decided to try out Snape's spell.

What is Snape sick with? Does it have anything to do with the ritual? 

I hope Luna is okay. Nice that Harry was able to use the DA coins to check in with his friends.

I was thinking that if Harry knew the spell for a stretcher he could put Snape on it and have it follow his if he walked or flew.

They need to eat more than croissants and biscuits. No protein would make them fatigued as well... maybe they can raid a home for some canned beans or meat?

Some corrections I noticed:

Harry sent out a wise-spread Depulso 

wide-spread

He turned his back on the thunderous but slightly confused Snape gave at this 

confused look

Woah this is awesome! Very unique premise! I love it!

Snape definitely should take Harry to the ritual site. 

Harry has his broom. They just need another broom and then they could fly. Or do zombies interfere with broomsticks?

The poor Muggle owner. Sounds like he's just given up.

I love how Snape refuses to call the creatures Zombies. 

Surely St Mungoes is working on a cure. Right? The Muggles reaction will be to just bomb and destroy everything. All the major cities once infected.

This is the read and cross-over I didn't know I needed. Thanks so much for sitting down and writing it down and sharing it! Such a fun story so far. I'm really enjoying it.

By the way, I edited the formatting of your story to fix the random breaks that were not indented.