Desperado by Sandra Hill is one of five of her novels included in the Timeswept series.  (Please let me know if there are more.)

For those with sharp eyes who are avid readers you will spot the stars of
Frankly, My Dear... in this novel, just as Helen and Rafe make a fleeting appearance in Selene's life.
 

This is (at the time of writing) the only novel I have read where the two main characters time travel together at the beginning of the novel.  Many have one or the other travelling after their true love, but this is the first I can recall where both the hero and heroinne time travel at the start.

This rules out reasons of death, dreaming, and most of the other explanations the time traveller imagines before reality returns.

Major Helen Prescott and Captain Rafael  Santiago find themselves thrown together again 12 years after graduation.  Still attracted to each other and still denying their feelings they are not prepared for an unscheduled parachute jump into the California Gold Rush.

Rafe is mistaken for the infamous Angel Bandit and Helen his sensuous mistress Elena.  What more could go wrong?  A lot more.

After all Elena is an expert at corkscrewing and their captors expect Helen to oblige.   And Rafe is supposed to be a bandit, pity he never learnt how to ride a horse.

Thrown together by fate, they soon admit their feelings for each other, but their problems are by no means over.  Convinced that a further parachute jump from the cliffs is the route back to the future Helen is determined to return at once.  Rafe on the other hand sees the Gold Rush as an opportunity to make enough money to pay his families debts.

With prejudice and suspicion at every turn Helen and Rafe must fight for a future together and overcome their differences once and for all.

RATING : 
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Links to  online stores

Also by Sandra Hill:  Frankly, My Dear..., The Reluctant Viking,  Sweeter Savage Love,  The Last Viking, The Outlaw Viking, The Bewitched Viking, Truly, Madly Viking, The Very Virile Viking, The Tarnished Lady, The Blue Viking, Tall, Dark & Cajun and The Love Potion

Read an interview with Sandra Hill.

Read more about Sandra Hill's books at her  web page.