Magnum wird von Melissa Wainwright angeheuert, den Tod ihres Vaters William zu untersuchen. Sie ist davon überzeugt, dass ihr Bruder Arthur etwas mit der Sache zu tun hat und im Besitz des Testaments ist. Bei seinen Ermittlungen trifft Magnum auf Susan Johnson, frisch gebackene Absolventin der Schule für Privatdetektive. Arthur hat sie beauftragt, ebenfalls nach dem vermissten Testament zu suchen. Denn der wiederum glaubt, dass Melissa es gestohlen hat. Nachdem Magnum und Susan sich erst einmal gehörig in die Quere kommen, beschließen sie zusammenzuarbeiten, denn die Angelegenheit wird immer mysteriöser. Tatsächlich könnte es sein, dass William Wainwright noch lebt!
Magnum is hired by an attractive woman to find the missing will of her late father, who was recently killed in a suspicious boating accident – which she suspects her brother of being behind, in order to steal the will. Working on the case, Thomas finds that former client Susan Johnson – whom he was once locked in a bank vault with – is now a fellow Private Investigator, and is working on the same case – for the brother, who suspects his sister as responsible for their father’s death. The two P.I.s are soon locked in a battle of wills as they both race to solve the investigation first, but the pair are forced to put their rather love-hate relationship to one side and team up to solve the case of sibling rivalry...
Magnum est engagé par Melissa Wainwright dont le père serait tombé de bateau et se serait noyé. Elle est persuadée que son frère Arthur est responsable de sa mort et qu'il a volé le testament...
Magnum viene assunto da una donna attraente per ritrovare il testamento scomparso di suo padre, di recente ucciso in un incidente nautico molto sospetto. Indagando sul caso, Thomas s'imbatte in una vecchia conoscenza, Susan Johnson, la quale si è lanciata nell'attività di detective e sta seguendo il caso per conto del fratello della cliente di Magnum. I due P.I. fanno a gara per vedere chi la spunta per prima, ma Thomas e Susan devono mettere da parte la loro rivalità per risolvere il caso
