Pony Pals, Ponies from the Past by Jeanne Betancourt is a great book in the Pony Pals series. While on Pony Pal Trail, the girls find a tree blocking their path. All over there are down trees from a huge storm that rolled through Wiggins. Normally the girls just jump their horses over obstacles in their path but Lulu’s horse, Snow White won’t jump. Something has got her attention and Lulu hops off to see what it is. On the ground, next to the fallen tree is a very old bottle with a letter inside.

Curious the girls open the jar to examine the letter. They are amazed when they read the date of 1918 at the top of the page. The letter is written by what they are guessing is a young girl. She is very sick with influenza and someone is bringing these letters to a secret hiding spot in the tree for her best friend to find. They have no idea who the girls are in the letter since the girls only use their initials in the letter. One thing the girls know is that the tree belongs to the Wiggins property and the girl writing the letter has the initials “AW.” Maybe Ms. Wiggins knows who “AW” is and can shed some light on this mystery.

The girls get excited when Ms. Wiggins tells the girls that “AW” was her great aunt who passed away years ago. Ms. Wiggins doesn’t know who “LS,” the other girl in the letter is though. According to what is written on the old paper, “AW” keeps all the letters her friend leaves her in her sewing basket and Ms. Wiggins gives the girls permission to look up in the attic. Their search turns up nothing and they can’t see a thing. All the lights are burned out. Ms. Wiggins suggests the girls head to the town hall as they would have a record of everyone born in Wiggins that year.

Sure enough, they only find one girl with the initials “LS” in the registry that was born the same year as Ms. Wiggins’ great aunt. The girls’ excitement only lasts for so long. They want so much to know if “LS” is still alive and are holding back tears to think that she may have passed away due to influenza as so many others did in 1918. Now they are on a mission to find “LS” and return the letter to the right full owner.