“Falling for Anthony” in HOT SPELL opens the Guardian series. It is set in 1811, England. If you are starting here, there is not any background to the series that won’t appear in the novels. An introduction to the Guardian mythology and history would not be out of place, however, so that is what I’m giving here.
In the First Battle, Lucifer led his rebels against Heaven. In punishment, they were transformed into demons and tossed into Hell. There were also angels who refused to take sides during the First Battle; these angels were transformed into nosferatu, cursed with bloodlust and vulnerability to daylight, and sent to Earth.
The seraphim who lived in Caelum watched over humans, and protected them from demons and nosferatu. The seraphim could never completely pass for human, however, and so the people on Earth began worshipping them as gods. When Lucifer realized this, his jealousy led him to wage another war against the angels, the Second Battle.
This battle took place on Earth, and Lucifer had with him a dragon from Chaos, and hellhounds. The angels began to falter before the dragon — but mankind, witnessing the battle taking place, joined the angels. One man, Michael, managed to destroy the dragon by cutting through its heart with his sword.
After the Second Battle, the seraphim retreated from Caelum, and gave Michael the power to guard humans on Earth, and to transform other men into Guardians. Because they were once men, Guardians can pass as human, and walk among those they protect.
What you need to know before reading “Falling for Anthony”: technically, nothing. But it doesn’t hurt to know that, at some undetermined point in the past, Michael’s sword–which absorbed some of the power of the dragon’s blood–was lost.