General Synonyms:
* Engrossing
* Compelling
* Intriguing
* Thrilling
* Exciting
* Spellbinding
* Captivating
* Absorbing
* Alluring
More Specific Synonyms:
* Heart-stopping (for suspenseful stories)
* Nail-biting (for suspenseful stories)
* Page-turner (for stories that keep you reading)
* Riveting (for something that holds your attention)
* Enthralling (for something that completely captivates you)
Synonyms related to a physical grip:
* Tight
* Strong
* Firm
* Secure
The best synonym for "gripping" will depend on the specific situation and what you want to emphasize.