Triangulation tells the dramatic story of three people: John Hopkins, a retired mapmaker who spent 40 years of his life helping England chart her many territories and provinces; Laurance Wallace, his handsome, well-born roommate who explored 1950's Africa on behalf of the British government; and Helen Gardner, the woman they both loved. A mis-sent letter sends Hopkins on a journey to find Helen, and into his own past, and as the novel unfolds we learn of the tragedy that changed all their lives forever.