Distress Signal by Elizabeth Goddard

Perilous reunion at sea...

When shipwreck archaeologist Cora Strand is attacked and the research boat she's on explodes, her ex comes to her rescue. Years ago, Kirk Higgins forfeited her heart, and now with no memory of who attacked her, Cora must trust him with her life. But at the risk of blowing his cover, can the NCIS agent stop a killer determined to put them both in a watery grave?