The Guardian by Kimberly Kincaid

Guard against any danger. Especially if it comes from within.

Detective Matteo Garza doesn't just do the job--he is the job. He's learned the hard way that work and pleasure can't co-exist.

So when his little sister's best friend accidentally uncovers a money laundering scheme led by one of Remington's most cold-blooded criminals, Garza vows to keep things strictly business as he keeps her safe.

No matter how much the quirky mathematician makes him feel things best left buried.
No matter how much she makes him want.

Delia Sutton knows she's not like most people, just like she knows she needs to forget her ages-old crush on Matteo
and focus on survival.
But the closer they get, the bolder she becomes--the more she breaks down his carefully crafted barriers to discover the man beneath.

Danger is closer than either of them could possibly imagine
and no one can be trusted.
Delia needs a guardian to fight by her side, and Matteo will do anything to protect her.
No matter who the enemy is.

The Guardian is a scorching forbidden lovers romantic suspense featuring a grumpy Alpha hero who would walk into fire to save the woman he loves and a smart-is-sexy number-nerd heroine who would save him right back. Equal parts heart-pounding suspense and steamy romance. Complete standalone with no cheating and a full (but hard-fought!) HEA.