One possible plot could be that Harry uses his magic in ways that are unexpected in the Middle - earth setting of Helm's Deep. Maybe he uses spells like 'Protego Maxima' to create a shield around the fortress, protecting it from the incoming orcs. He could also use the 'Accio' charm to bring weapons to the defenders when they are in need.
He could use his flying skills on a broomstick to scout the enemy. Just imagine Harry on his Firebolt, flying high above Helm's Deep, seeing the approaching army of orcs and relaying the information back to the defenders.
One possible plot could be that Harry and his friends accidentally get transported to the Battle of Helm's Deep. They use their magic to turn the tide of the battle in unexpected ways. For example, Hermione could use a spell to make the walls of Helm's Deep even stronger, while Harry and Ron lead a group of wizards to fight off the orcs from above using broomsticks.
Obviously, Harry Potter himself would be a main character. He could bring his skills and courage from the wizarding world to the Battle of Helm's Deep. Hermione Granger would also be there. Her vast knowledge of magic could be crucial in finding solutions during the battle. Ron Weasley too, with his loyalty and his own brand of wizarding skills. Maybe Hagrid could also be involved, his huge size and strength being an asset in the physical combat at Helm's Deep.
We can recommend the following novels similar to Helm:
1. [Chongzhen eavesdropping system]
2. "Song Man in the Box"
3. The Doomsday Game in the Box
4. " Strategy for the Revival of the Northern Song Dynasty."
5. "Ming from..."
Please note that these novels may be similar to Helm in some ways, but the specific content and style may be different.
Gandalf originated from a higher spiritual plane. He was dispatched to Middle-earth with a purpose. His background involves being part of a divine order and having a responsibility to bring hope and resistance against evil.
Gandalf is a Maia. He was sent to Middle - earth by the Valar. He was one of the Istari, a group of wizards. His purpose was to guide and oppose the rising power of Sauron.
Well, 'Death of a Citizen' is also among the best Matt Helm novels. It really sets the tone for the series. It shows Helm's skills as an agent in a world full of danger and mystery. The story is well - paced and the characters are well - developed.