In Zellner v. Wassman (1920) 184 Cal. 80, the Supreme Court explained: "Agreements to leave property by will often consist of promises to devise real property in return for peculiar personal services, or other consideration . . . . The fact remains, however, that, in actions upon these agreements, as in other actions upon contracts, inadequacy of the legal remedy to compensate for the breach is the keystone of equitable jurisdiction. Since plaintiff relies upon an alleged contract to bequeath a specified sum of money, the case falls within the decision of this court in Morrison v. Land, 169 Cal. 580 where it was said: 'An ordinary action at law for breach of the contract would bring him the very thing to which he is entitled under the allegations of his complaint . . . .' " (Zellner, supra, 184 Cal. at p. 84.)