What's the Name of That Book??? discussion

I've gotten the titles of all books I've been looking for here (except one), so I'm pretty sure someone will help me find this one too.

A young woman named Amanda is the main character. She has an elderly aunt and a boy friend. Her aunt had bought a rather isolated home which has a hidden bomb shelter, about which she didn't know. Her aunt also owns a dog and a horse. One of the workmen who worked on the shelter, however knows about the secret bomb shelter. The workman's brothers name is Claude, and this brother gets obsessed with a girl named Ellie Peale, who works in a convenience store. before the story begins, Claude kidnaps Ellie. The police are after him, and he calls his brother for help. The plot is set in Albuquerque.

When the story begins, Amanda has agreed to look after one of her Hispanic friend's (the Lopez family?) young 3 year old daughter who isn't well enough to travel on a plane, while her parents visit their families. Amanda gets a phone call from a hospital that her aunt had a stroke and is unconscious. Amanda, this, has the responsibilities to look after both the baby girl and her Aunts pets. She takes the baby to her Aunts home.

The action starts when Claude, who has been hiding in the bomb shelter comes out late night and Amanda hears him.

Its a really thrilling book and I would appreciate anyone who could hell identify the title and author.

I think is may be Dig A Little Deeper by Ursula Curtiss. The links on Goodreads are a little confusing. Not sure if the book is also titled "The Birthday Gift" or if that is a completely different book by Curtiss.

Digging (heh) around on Google Books, I found I small paragraph

A killer hiding in a secret basement of her invalid aunts house, terrorizes Amanda Morley and Rose, a two year old in her care in the chiller by author of "The Birthday Gift" and "In Cold Pursuit."

Wow, thank you, Tab. Your "digging" (nice pun, by the way!) produced pay dirt....

The paragraph you quote belongs to same exact story I was looking for. The book is written by Ursula Curtiss, but the title was The Menace Within.

Yet another book solved. This group and it's members are awesome!