[eng] Being able to transmit coherent messages through oral and written communication in the target language has become the primary goal in English as a Foreign Language (EFL) education. In fact, the teaching of EFL has been influenced by the rapid changes society experienced in the last decades due to technological advances. For this reason, implementing the Task-Based Learning methodology in EFL high-school lessons seems fitting to promote the ability to communicate with others by proposing a specific context in which students will need to cooperate in the target language to fulfil the task. To achieve that, appropriate channels that accommodate the current human interaction are social media platforms. In this way, this paper aims at examining and analysing the effects of utilising Telegram, an instant-message phone application, in a thirdyear secondary education classroom in Spain (3rd of ESO). This theory is studied in the didactic proposal this dissertation presents, which is centred in the development of a task composed of three activities. The theories reviewed are utilised as the supporting initial point on the reasoning why the development of this teaching proposition is conceivable and beneficial for students’ language acquisition. This proposal revolved around the engaging aspects a Solve a Mystery activity can cause in students’ motivation, by exchanging information and clues either in class or in digital spaces. Furthermore, to confirm the hypothesis a questionnaire was conducted to learn about students’ perspectives. This survey analysed students’ previous experiences and it allowed them to acquire further knowledge on their perceptions regarding the tasks. The results obtained indicated the success achieved through this approach as participants were motivated to participate and further develop their language knowledge.