Blood Tide - Better Swash-buckling Through Chemistry by D. J. Bershaw

On leave, in trouble, and with their twin daughters along for the dangerous thrill-ride. Not unusual for Majors Megan Connolly and Farrell Gray, Special Forces vampires. An old friend's family needs help protecting a hundreds-of-years-old medical secret which could change the world of medicine forever. After over-coming environmental terrorists, Indian activists, a giant prehistoric bear, and some old misconceptions, they face the armed might of a multinational German pharmaceutical company with extremely bad intentions.